TECHNICAL FIELD

This invention relates to a system and a corresponding method for performing an objective cleaning control in a food manufacturing facility/production site, e.g., a production line in a slaughterhouse. The system of the invention may be characterised by comprising several essential elements incl. an UV-light source, an UV-sensitive camera, a visible light camera, a visible light source, a processing means, a monitoring device, and a storage device.

BACKGROUND ART

Cleaning and disinfection are key steps in a food production, as it helps to ensure high food safety and optimal shelf life of the products. In the meat industry, the daily cleaning control is primarily visual/tactile, often supplemented with ATP (Adenosine TriPhosphate) methods and microbiological tests.

Visual observation is an important and effective method that is often used in a busy working environment, but this method has two clear drawbacks: It is subjective and depends on the eye of the beholder, and it is difficult to quantify.

There is a need for a measurement principle that can help companies make a quick, objective assessment of the level of cleaning in the production setting.

WO2017144338 describes an automated tool for analysing a plurality of biological samples with a plurality of fluorescent reagents in an automated fashion.

WO2019086557 describes an inspection apparatus for inspecting a flow of a product using fluorescence, in particular for characterizing products having mycotoxin contamination.

US2019308762 describes an inspection device for detecting a foreign substance adhering to the inner surface of a container by measuring the fluorescence emitted the substance in response to an excitation light projected onto the substance.

EP3581920 describes a cleaning-performance evaluation system that can acquire evaluation results in real time as quantitative values relative to a mock contaminant.

W02020096890 describes a system for monitoring the amount of biological material cleaned from medical devices and to determine when cleaning is complete.

EP3660492 describes a fluorescent penetrant inspection system for inspection of work pieces using fluorescence to detect defects.

However, the system and method according to the present invention have never been disclosed. SUMMARY OF THE INVENTION

We have developed an objective measurement principle that can help companies make a quick, objective assessment of the level of cleanliness in a food manufacturing facility, e.g., in a slaughterhouse or in the meat processing industry, for production of fresh or processed meat, e.g., a production room, or for assessing and quantifying the level of cleanliness of processing equipment.

The present invention is based on the principle of using fluorescence detection in the UV range, that we have found applicable and functional for integration into a hand held device, or it may be capable of being conveyed in a production facility by an autonomous vehicle or by a pre-programmed conveying system.

Using fluorescence detection in the UV range it has been proven possible to obtain a significant signal from both fresh and processed meat, and, in addition, ordinary surfaces used in the meat producing industry have negligible autofluorescence.

The present invention provides a system that can be used in a fully lit room, and that is compact enough to monitor even hard-to-reach corners. Moreover, the device of the present invention can distinguish dirt particles/meat residues, e.g., from handling raw or processed meat, from the most common surfaces, and can determine whether the cleanliness is above or below a given threshold. Once the threshold has been set, the device can thus assess, in an objective way, whether a surface is sufficiently clean.

The system of the invention may strengthen the registration of the cleaning efficiency, help with reporting of the level of cleanliness and provide software for data processing, e.g., trend analysis over time.

An objective assessment of purity not only is beneficial to a company's own hygiene monitoring program, but can also promote communication with other parties, including cleaning staff, inspectors from authorities, as well as auditors from clients and third-party certification bodies.

Therefore, in its first aspect, the invention provides a vision system, for objective determination of the cleaning level at an inspection site in a food production facility, which system comprises the following essential elements: a. an UV-light source (2), for excitation of dirt particles/meat residues (8) present in the production facility, which UV-light source (2) is capable of emitting light in the range of from about 300 to about 310 nm, and which light source is further equipped with a low-pass light filter (2A) having a cut-off value of for light emission over 315 nm; b. an UV-sensitive camera (3), in operation with a processing means (6), for detecting the level of fluorescent emission originating from the dirt particles/meat residues present in the production facility, which UV-camera is capable of detecting radiant fluorescent light in a range of from about 330 to 380 nm, and which UV-camera is further equipped with a band-pass light filter (3A) capable of allowing only light with a wavelength in the range of from about 330 to about 380 nm to pass; c. a visible light camera (4), in operation with a processing means (6), for generating a visual light image of the inspection site (10); d. a visible light source (5), capable of emitting a sufficient level of visible light; e. a processing means (6), in operation with the UV-sensitive camera (3), with the visible light camera (4), with the monitoring device (7), with the storage device (8), and, optionally with the rangefinder (9), which processing means (6) is configured for, and capable of creating a parallel image or digitally overlaying an image of the inspection site (10) obtained by the visible light camera (4) with a corresponding image of the inspection site (10) obtained by the UV-sensitive camera (3); f. a monitoring device (7), in communication with the processing means (6), configured for displaying video recordings from the visible light camera (4) and recordings from the UV-sensitive camera (3); and g. storage device (8), in operation with the processing means (6), configured for storing i.a. image information and measurement parameters.

In another aspect the invention provides a method for objectively determining the cleaning level at an inspection site (10) in a food manufacturing facility/production site, which method comprises the subsequent steps of: i. subjecting the inspection site (10) to UV-light emitted from an UV-light source (2) capable of emitting light in the range of from about 300 to about 310 nm, and which UV-light source (2) is further equipped with a low-pass light filter (2A) having a cut-off value of for light emission over 315 nm; ii. detecting light in the range of from about 330 to about 380 nm, emitted from the inspection site (10), by use of an UV enhanced camera (3), which UV-camera is further equipped with a band-pass light filter (3A) capable of allowing only light with a wavelength in the range of from about 330 to about 380 nm to pass; and iii. creating a visual image with a visible light camera (4) used for displaying parallel to or overlaying fluorescens information from the UV camera (3).

Other objects of the invention will be apparent to the person skilled in the art from reading the following detailed description and accompanying drawings.

Any combination of two or more of the embodiments described herein is considered within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further illustrated by reference to the accompanying drawing, in which:

Fig. 1A illustrates one embodiment of the vision system of the invention;

Fig. IB illustrates another embodiment of the system of the invention;

Fig. 2 illustrates another embodiment of the system of the invention, mounted on a stand with a fixed distance to the object to be examined (here a conveyor belt); and

Fig. 3 shows the light intensity difference, i.e. the difference between signal and background noise, for baloney on a wet stainless steel surface measured in the interval 280 - 800 nm, by use of a fluorescens spectrophotometer.

DETAILED DISCLOSURE OF THE INVENTION

The system of the invention

It its first aspect, the invention provides a vision system (1) for objectively determining the cleanliness level in a food production facility by determining the level of soiling, i.e., unwanted dirt particles/meat residues, at an inspection site in the production facility.

The system of the invention may be characterised by comprising the following essential elements: a. an UV-light source (2), for excitation of dirt particles/meat residues (11) present in the production facility, which UV-light source (2) is capable of emitting light in the range of from about 300 to about 310 nm, and which light source is further equipped with a low-pass light filter (2A) having a cut-off value of for light emission over 315 nm; b. an UV-sensitive camera (3), in operation with a processing means (6), for detecting the level of fluorescent emission originating from the dirt particles/meat residues present in the production facility, which UV-camera is capable of detecting radiant fluorescent light in a range of from about 330 to 380 nm, and which UV-camera is further equipped with a band-pass light filter (3A) capable of allowing light with a wavelength in the range of from about 330 to about 380 nm to pass; c. a visible light camera (4), in operation with a processing means (6), for generating a visual light image of the inspection site (10) [ which visible light camera (4) is capable of detecting visible light in the range of about 400 to about 700 nm]; d. a visible light source (5), capable of emitting a sufficient level of visible light; e. a processing means (6), in operation with the UV-sensitive camera (3), with the visible light camera (4), with the monitoring device (7), with the storage device (8), and, optionally with the rangefinder (9), which processing means (6) is configured for, and capable of digitally creating a parallel image or overlaying an image of the inspection site (10) obtained by the visible light camera (4) with a corresponding image of the inspection site (10) obtained by the UV-sensitive camera (3); f. a monitoring device (7), in communication with the processing means (6), configured for displaying video recordings from the visible light camera (4) and recordings from the UV-sensitive camera (3); and g. storage device (8), in operation with the processing means (6), configured for storing i.a. image information and measurement parameters.

In another embodiment, the system further comprises a rangefinder/distance meter (9) for measuring of the distance from the inspection site (10) to the UV-sensitive camera (3), which rangefinder enables intensity correction of the fluorescence measurement in relation to varying distance between the two objects (i.e., the measuring object and the UV-sensitive camera).

In a further embodiment, the system is mounted on a stand located above the inspection site/measuring object (e.g., a conveyor belt), and which has a fixed distance to the measuring object, for continuous monitoring of soiling levels building up on the inspection site (10), e.g., on a conveyor belt.

The system of the invention may be applied to an inspection site in a food production facility, e.g., a food manufacturing facility, for the processing of raw or processed meat products.

In another embodiment, the food production facility is a production line established in a slaughterhouse.

The UV-light source

For fluorescent excitation of the dirt particles/meat residues (11) present in the production facility, the system of the invention shall comprise an UV-light source (2), i.e., a fluorescens excitation lamp, capable of emitting light in the specific range of from about 300 to about 310 nm.

In one embodiment, the UV-light may consist of powerful diodes. The use of diodes as flash-lamps enables sending very strong currents through the diodes, thereby achieving a much more intense lighting than is normally possible for this type of diode, and with minimal risk of them over-heating.

The low-pass filter

To prevent light from the excitation light source from over-powering the emission from the dirt particles/meat residues in the UV region of from about 330 to about 380 nm, the light source shall be equipped with a low-pass filter (2A) having a cut-off value of for light emission over about 315 nm, i.e., a filter that blocks all frequencies above 315 nm.

The low-pass filter (2A) is needed, as the UV-source having a centre wavelength of 308 nm emits 95% of the light in the wavelength range 300-315 nm. The remaining 5% of the light is emitted at longer wavelengths, typically 215-500 nm, and this light may be strong enough to drown out the relatively weak fluorescence emission that the instrument must be able to detect.

The light source filter therefore should be able to admit passing of more than 80% of the light in the wavelength range of from about 300 to about 315 nm, and as a minimum be able to suppress wavelengths above 320 nm by a factor of 10000.

In one embodiment, and because the fluorescent light coming from the UV-light source is very weak compared to the ambient light, the filter in front of the UV-sensitive camera should be able to suppress wavelengths below 320 nm by a factor of 10.000 (Optical Density, OD 5), and equivalent for wavelengths above 380 nm by a factor of 10.000 (OD 5).

The UV-sensitive camera

For detecting the level of fluorescent emission originating from the dirt particles/meat residues (11) present at an inspection site (10) in the production facility, the system of the invention shall comprise an UV-sensitive camera (3), capable of detecting fluorescent light in a range of from about 330 to about 380 nm, e.g., of around 350 nm, with good quantum efficiency.

In one embodiment, the UV-sensitive camera (3) for use according to the invention is an UV-enhanced area scan camera.

To ensure a sufficient selectivity in this specific range, the UV-camera shall be equipped with a band-pass filter (3A), e.g., in front of the lens, capable of allowing only light having a wavelength in the range of from about 330 to about 380 nm to pass, and capable of cutting of light of lower/higher wavelengths.

For making the UV-sensitive camera (3) undisturbed by light emitted from the UV-light source (2) (i.e., the fluorescens excitation lamp) and undisturbed by ambient day light or artificial light in the room, this filter (3A) in front of the UV camera must filter out the visible light so that it only sees the fluorescence emission from 330nm to 380nm, while also removing the direct light from the UV light source (2).

In one embodiment, the band pass filter (3A) has a transmission better than

80%. The visible light camera

For creating a recognizable image of the surroundings, the system of the invention also shall comprise a regular visible light camera (4).

Regular visible light cameras (4) for use according to the invention normally can detect visible light in the range of from below 400 to above 700 nm.

The image recorded by this visible light camera (4) for use according to the invention is used to create an overlay image for the fluorescens detected by the UV- sensitive camera (3), so the detected dirt particles/meat residues (11) easily can be identified on the measured surface area (10).

In one embodiment, the visible light camera (4) for use according to the invention is a standard (industrial) camera.

In another embodiment, the required calculations for overlaying fluorescens images from the UV-sensitive camera (3) with a visual image, applying thresholds for florescence emission and distance correction, can be made with a smartphone/tablet processor (4).

In another embodiment, the visible light camera (4) for use according to the invention is a tablet/smart phone.

Visible light source

For the regular, visible light camera (4) to be able to record images, some level of visible light must be present. Visible light may occur in the form of ambient light, but can also, advantageously, be supplemented with an ordinary visible light source (5).

In one embodiment, the visible light source (5) for use according to the invention shall be capable of emitting light in the range of from about 400 to about 700 nm.

The processing means

The system of the invention shall comprise a processing means in communication/function and/or operation with the UV-sensitive camera (3), with the visible light camera (4), with the monitoring device (7), with the storage device (8), and, optionally with the rangefinder (9).

The processing means (6) for use according to the invention shall be configured for, and capable of i.a. digitally overlaying an image of the inspection site (10) obtained by the visible light camera (4) with a corresponding image of the inspection site (10) obtained by the UV-sensitive camera (3).

This technique of receiving related image information from both cameras enables the operator of the system to be able to see what object is being pointed at. The processing means (6) for use according to the invention shall be configured for processing, analysing, and communicating data and information wireless via e.g., Wi Fi or Bluetooth, or storing it on an internal memory, and therefore shall also be in communication/function and/or operation with the storage device (8).

The processing means (6) for use according to the invention shall be configured for applying threshold values to the corrected UV-image to locate areas of dirt particles/meat residues.

In one embodiment, a protocol may define that if the fluorescence signal is higher than a selected value, this represents an unacceptable level of soiling.

In another embodiment, the processing means (6) for use according to the invention shall also be in communication with the rangefinder (9), and configured for calculating distances to the object, and to calculate the relevant correction to the fluorescence signal.

In a further embodiment, the processing means (6) for use according to the invention shall also be in communication with the UV-light source (2) and shall be configured for and capable of switching on or off the UV-light (2). This may be useful when the operator wants to analyse the measuring area shown on the screen.

The processing means/CPU (6) for use according to the invention may be any commercially available processor or PC, and could also be an integrated part of e.g., a smartphone.

The monitoring device

For visualising the cleaning level at the inspection site (10) the system of the invention shall comprise a monitoring device.

The monitoring device (7) for use according to the invention shall be in communication with the processing means (6) and be configured for continuously displaying video recordings from the regular, visible light camera (4) along with the parallel displayed or overlayered recordings from the UV-sensitive camera (3).

In one embodiment, the monitoring device for use according to the invention is a screen included in a smartphone.

The storage device

For storing i.a. image information, measurement parameters, etc. the system of the invention shall comprise a storage device (8), and the storage device for use according to the invention shall be in communication/function and/or operation with the processing means (6).

The storage device may also be considered a digital platform, i.e., a server system, optionally a cloud-based solution, capable of communicating with various access points, and configured for receiving and processing digital information via a wireless (Wi Fi) communication network.

In one embodiment, the storage device for use according to the invention is the storage space or memory included in a smartphone.

The rangefinder/distance meter

In one embodiment, the system of the invention may be designed as a construction with a fixed distance to the object to be examined, e.g., relative to a conveyor belt.

However, light intensity decreases by a factor of 1/r ² (where r represents the distance to the object).

Therefore, in another embodiment, the system further comprises a rangefinder/distance meter (9), in communication with the UV-sensitive camera (3), the visible light camera (4), and/or with the processing means (6), for measuring of the distance from the inspection site (10) to the UV-sensitive camera, which rangefinder enables intensity correction of the fluorescence measurement in relation to varying distance between the two objects (i.e., the measuring object and the UV-sensitive camera).

The vision system of the invention is for objective determination of the level of cleanliness at an inspection site (10) in a food production facility.

The place of inspection (10) may be a surface area, or a particular object located within the production facility, e.g., a conveyor belt.

In one embodiment, the inspection site (10) is a surface area in the production facility, e.g., a wall in the facility, a machine in the facility, or equivalent piece of interior.

In another embodiment, the inspection site (10) is a conveyor belt which transports food products, and the vision system of the invention inspects the level of soiling (11) on the products while they are on the fly.

The method of the invention

In another aspect, the invention provides a method for objectively determining the level of cleanliness at the production site in a food production facility by determining the level of unwanted dirt/meat residues. The method of the invention may be characterized by comprising the subsequent steps of: i. subjecting the inspection site (10) to light emitted from an UV-light source (2) capable of emitting light in the range of from about 300 to about 310 nm, and which UV- light source (2) is further equipped with a low-pass light filter (2A) having a cut-off value of for light emission over 315 nm; ii. detecting light in the range of from about 330 to about 380 nm, emitted from the inspection site (10), by use of an UV-sensitive camera (3), which UV-camera is further equipped with a band-pass light filter (3A) capable of allowing light with a wavelength in the range of from about 330 to about 380 nm to pass; and iii. creating a visual image with a visible light camera (4) used for displaying parallel to or overlaying fluorescens information from the UV-sensitive camera (3).

In another embodiment, the method of the invention further comprises the following step: iv. continuously measuring the distance from the inspection site (10) to the UV- sensitive camera (3) by use of a rangefinder/distance meter (9) to enable a distance correction to the fluorescens measurement.

The method of the invention may be applied to an inspection site in a food manufacturing facility, e.g., a facility, for the manufacturing of raw or processed meat products.

In another embodiment, the food production facility is a production line in a slaughterhouse.

DETAILET DESCRIPTION OF THE DRAWINGS

The present invention is further illustrated by reference to the accompanying drawing, in which:

Fig. 1A illustrates one embodiment of the vision system of the invention: UV-light source (2) equipped with a low-pass light filter (2A); UV-sensitive camera (3) equipped with a band-pass light filter (3A); Visible light camera (4); Visible light source (5); Processing means/processing unit (6); Monitoring device (7); Electronic storage device (8); and Rangefinder/distance meter (9);

Fig. IB illustrates another embodiment of the system of the invention : UV-light source (2) equipped with a low-pass light filter (2A); UV-sensitive camera (3) equipped with a band-pass light filter (3A); Smartphone comprising a visible light camera (4), a processing means (6) and a monitoring device (7); Visible light source (5); Electronic storage device (8); and Rangefinder/distance meter (9); Fig. 2 illustrates another embodiment of the system of the invention, mounted on a stand with a fixed distance to the object to be examined (here a conveyor belt): UV- light source (2), e.g., an UVB lamp, 308 nm, equipped with a low-pass, 315 nm edge, light filter (2A); UV-sensitive camera (3, e.g., equipped with a 325-380 nm band-pass light filter (3A); Rangefinder/distance meter (9) measuring the distance from the UV-light source (2) to the conveyor belt (10); Conveyor belt (10) with contamination (11); and

Fig. 3 shows the light intensity difference, i.e., the difference between signal and background noise, for baloney on a wet stainless-steel surface measured in the interval 280-800 nm, and suggest the capture of light signals in the range of from approx. 330 nm to approx. 380 nm by use of a fluorescens spectrophotometer, and shows that an excitation at approx. 310 nm creates a good separation between the signal noise coming from a possible autofluorescence from the surface, and the signal for the instrument to detect, coming from the dirt particles/meat residues.

List of reference signs

This is a listing of various elements relating to the present invention and shown in the appended figures. Alternative/synonymous designations are separated by slashes.

1. The system of the invention

2. The UV-light source/fluorescens excitation lamp

2A. Low-pass light filter for UV-light source

3. UV-sensitive/enhancing camera

3A. Band-pass light filter for UV-sensitive camera

4. Visible light camera/standard camera

5. Visible light source/ambient light

6. Processing means/processing unit

7. Monitoring device/video screen

8. Electronic storage device/server/hard disk/PC

9. Rangefinder/distance meter

10. Inspection site/surface area/measuring object, e.g., a conveyor belt

11. Dirt particles/meat residues