Inspection system and method

Abstract

A product inspection system comprising: i) a product conveyor line (2); ii) an inspection means (3) for inspecting products positioned along the conveyor line (2). The inspection means (3) comprises: a front lighting means (31) for frontally illuminating the products; said front lighting means (31) emitting electromagnetic waves having a plurality of wavelengths; a backlighting means (32) for illuminating the products from behind; a hyperspectral camera (33) that acquires information during the passage of the products. The front lighting means (31) comprises a light source other than an LED; the backlighting means (32) comprises at least a first LED (321) which emits light at a predetermined wavelength.

Description

[0001] DESCRIPTION

[0002] INSPECTION SYSTEM AND METHOD

[0003] Technical field

[0004] The present invention relates to an inspection system and method.

[0005] Prior art

[0006] There are known inspection systems comprising a conveyor belt, a vision system for viewing products conveyed along a conveyor belt, a front lighting of the products (from above) and a backlighting of the products (from below the belt supporting the products).

[0007] Solutions in which the front lighting and the backlighting are provided by means of broad-spectrum halogen lamps are typically known. A drawback of this solution is tied to the fact that the front lighting is reflected towards the vision system and when added to the broad-spectrum light coming from the backlighting it would risk saturating the vision system. In order to avoid this drawback, the exposure time would need to be reduced, thereby reducing the signal received (or reducing the amount of light, with similar problems).

[0008] In an alternative known solution, synchronised pulsed-light LED illuminators are used for both the front lighting and the backlighting.

[0009] A drawback of this solution is tied to the fact that the synchronisation of the front lighting and backlighting LEDs introduces complications and costs. Moreover, there are difficulties tied to the width of the spectrum covered and to the little light available.

[0010] Aim of the invention

[0011] The aim of the present invention is to provide a product inspection system and method that allows for improving the gathering of information relating to the products passing through. A further important aim is to optimise the overall dimensions.

[0012] The stated technical task and specified aims are substantially achieved by a system and a method comprising the technical features disclosed in one or more of the appended claims. Brief description of the drawings

[0013] Additional features and advantages of the present invention will become more apparent from the approximate and thus non-limiting description of a preferred but not exclusive embodiment of a system and method as illustrated the appended drawings, in which:

[0014] - figure 1 shows a schematic view of a system according to the present invention;

[0015] - figures 2, 3, 4, 5 show tables relating to the signals detected by the system in figure 1 .

[0016] Detailed description of preferred embodiments of the invention

[0017] In the appended figures, a product inspection system is denoted by the reference number 1 . Advantageously, the products are food products, for example fruit or vegetables.

[0018] The inspection system 1 comprises a product conveyor line 2. For example, the conveyor line 2 can comprise one or more conveyor belts and / or a chute.

[0019] The system 1 also comprises an inspection means 3 for inspecting products positioned along the conveyor line 2.

[0020] The inspection means 3 typically comprises lighting means and means for acquiring data originating from the conveyed products.

[0021] The inspection means 3 comprises a front lighting means 31 for frontally illuminating the products. The front lighting means 31 emits electromagnetic waves of a different wavelength. In particular, the front lighting means is a broad-spectrum lighting means. The front lighting means 31 comprises a light source other than an LED.

[0022] By way of example, the front lighting means 31 for frontally illuminating the products comprises at least one halogen lamp 310 or at least one laser which emits light at different wavelengths (conveniently broad-spectrum). Typically, the laser is a supercontinuum laser (which is conveniently of a commercial type).

[0023] The inspection means 3 also comprises a backlighting means 32 for illuminating the products from behind.

[0024] The backlighting is opposite the front lighting. The front lighting means 31 and the backlighting means 32 illuminate the conveyor line 2 from opposite zones. Typically, the means 31 illuminates from above and the means 32 from below.

[0025] For example, the conveyor line 2 comprises a conveyor. Typically, the conveyor comprises a conveyor belt 20 which defines an upper product conveyance section 21. The conveyor belt 20 also comprises a lower return section (while the upper section 21 typically enables the forward feeding of products, the lower section does not involve the conveyance of products).

[0026] The front lighting means 31 is located at a greater height than said conveyor (in particular than said conveyor belt 20). The first LED 321 is located below the conveyor or at least below the upper section 21 .

[0027] The inspection means 3 also comprises a camera 33 which, during the passage of the products, acquires information on the latter. In particular, the camera 33 acquires information on the products during the passage thereof in a predetermined zone 200 of the conveyor line 2. This information can be, for example, physicochemical properties of the products and is obtained from an analysis of the detected spectra. The abovementioned camera 33 is a hyperspectral camera 33. Hyperspectral cameras 33 as such are known. The hyperspectral camera 33 is conveniently of a commercial type. A hyperspectral camera acquires an image and, for each pixel, the spectrum. Spectral information is acquired by the camera one line at a time.

[0028] Conveniently, a VNIR FX10 (400-1000 nm) camera is used. The camera 33 conveniently works in the visible and NIR (near infrared) light region.

[0029] At least one section of the conveyor line 2 (in particular the predetermined zone 200) is located between the hyperspectral camera 33 and the backlighting means 32.

[0030] The backlighting means 32 comprises at least a first LED 321. Conveniently, the first LED 321 emits light at a predetermined wavelength. Purely by way of non-limiting example, the wavelength is between 600 nm and 700 nm. Preferably, the wavelength is equal to 655 nm. Optionally, immediately downstream of the first LED 321 , there is a filter which allows the passage of a light having a narrow range of wavelengths. In the preferred solution, the first LED 321 is powered with a voltage of 4V and a current intensity of 70mA.

[0031] The hyperspectral camera 33 is on the vertical of the conveyor (or of the conveyor belt 20). In particular, the camera 33 lies on the vertical of the first LED 321. In particular, the camera 33 lies on the vertical of the predetermined zone 200 of the conveyor line 2 (in which it scans the products).

[0032] Advantageously, the backlighting means 32 comprises a second LED 322. The second LED 322 emits light at a predetermined wavelength. The second LED 322 emits light at a predetermined wavelength differing from that of the light emitted by the first LED 321 .

[0033] Preferably, the second LED 322 is positioned side by side with the first LED 321 . Conveniently, they are at a distance of less than 5 millimetres from each other. Conveniently, the first and second LEDs 321 , 322 emit light towards the line 2 and the camera 33. The light beams emitted by the first and second LEDs 321 , 322 are substantially parallel.

[0034] Conveniently, the first and second LEDs 321 , 322 can take on an operating mode in which they are both lit and emit a non-intermittent light. The first and seconds LED 321 , 322 can take on an operating mode in which one is intermittently lit, and the other one is non-intermittently lit.

[0035] The first and second LEDs 321 , 322 can take on an operating mode in which they are both intermittently lit (at the same frequency or not). In this manner, more detailed information can be obtained by comparing the received signals.

[0036] The system 1 comprises a data analysis means 4 for analysing the data acquired by said hyperspectral camera 33. Conveniently at least a part of the electromagnetic waves emitted by said front lighting means 31 has a wavelength equal to that of the light emitted by the first LED 321 .

[0037] Conveniently at least part of the electromagnetic waves emitted by said front lighting means 31 has a wavelength equal to that of the light emitted by the second LED 322.

[0038] Optionally, the system 1 can also comprise a rejection means which removes products that show undesirable anomalies from the conveyor line 2. The rejection means can comprise a mechanical element or a fluid jet that acts on the products to be rejected to remove them from the line 2. The rejection means is located along the line 2 downstream of the means 31 and 32. Conveniently, the rejection means is activated based on the information processed by the means 31 and 32.

[0039] The present invention also relates to a product inspection method. Typically, they are food products, for example vegetables or fruit (they are typically discrete products, distinct from each other). The method can be implemented by means of an inspection system 1 having one or more of the previously described features. The method comprises a step of conveying the products along a conveyor line 2.

[0040] The method also comprises a step of analysing the products located along the conveyor line 2 through an inspection means 3.

[0041] The step of analysing the products comprises the steps of:

[0042] - frontally illuminating the products by means of electromagnetic waves of a different wavelength (multifrequency) without the use of LEDs; this typically takes place by means of at least one halogen lamp or laser with a broad spectrum (supercontinuum lasers are known in the technical sector);

[0043] - backlighting the products by means of at least a first LED 321 .

[0044] The step of analysing the products comprises acquiring, by means of a hyperspectral camera 33, information during the passage of the products in a predetermined zone 200 of the line 2. The step of frontally illuminating the products comprises illuminating a first food product positioned in the predetermined zone 200 of the conveyor line 2; the first product belongs to said products; the step of backlighting the products comprises illuminating the first product positioned in said predetermined zone 200. The step of frontally illuminating the first product in the zone 200 and the step of backlighting the first product in the zone 200 takes place at least in part simultaneously.

[0045] The step of backlighting the first product in the zone 200 can envisage, for example, one of the following operating modes:

[0046] - the first and second LEDs 321 , 322 can take on an operating mode in which they are both lit and emit a non-intermittent light;

[0047] - the first and second LEDs 321 , 322 can take on an operating mode in which one is intermittently lit, and the other one is non-intermittently lit;

[0048] - the first and second LEDs 321 , 322 can take on an operating mode in which they are both intermittently lit (at the same frequency or not). In this manner, more detailed information can be obtained by comparing the signals received.

[0049] The method also comprises a step of processing the information gathered with the hyperspectral camera 33 to determine whether or not one of the products has passed through said zone 200 or to determine a property of a food product passing through said zone 200.

[0050] The above may be obtained by comparing the spectra obtained by the camera 33 when one of the products passes or does not pass through the zone 200. In particular, by comparing the part of the spectra at the wavelength of at least the first LED 321 .

[0051] The step of determining whether or not a product has passed through said zone 200 or of determining a property of a food product in said zone 200 comprises the steps of:

[0052] - determining at least a first value of a parameter associated with the intensity of the predetermined wavelength of the light emitted by the first LED 321 in a known configuration; for example, this is obtained by detecting the spectrum via the camera 33; the first value is for example the peak of the spectrum at the predetermined wavelength of the light emitted by the first LED 321 (in a known, for example calibration configuration, in the absence of the passage of a product in the zone 200);

[0053] - acquiring at least a second value of said parameter associated with the intensity of the predetermined wavelength of the light emitted by the first LED 321 in a configuration to be investigated (tied to the passage of one of said products in the zone 200); for example, this is obtained by detecting the spectrum via the camera 33; the second value is for example the peak of the spectrum corresponding to the predetermined wavelength of the light emitted by the first LED 321 in the configuration to be investigated (associated, for example, with the passage of a product in the zone 200);

[0054] - comparing the first and second values; for example, this is obtained by comparing the spectra.

[0055] Based on the distance between said at least a first value and said at least a second value, information can be obtained regarding the passage of a food product in said zone 200 or to determine a property of a food product passing through said zone 200.

[0056] For example, figure 2 shows a parameter associated with the intensity of the light intercepted by the camera 33 on the y-axis and the wavelengths on the x-axis. This figure relates to a situation in which there is no product in said predetermined zone 200. The two peaks that can be observed are tied to the lighting up of the first and second LEDs 321 , 322.

[0057] Assuming that the spectrum of the reflected signals is a vector comprising ten wavelengths, the contribution of the front lighting means 31 would be: X=[a1 , a2, a3, a4, a5, a6, a7, a8, a9, a10]

[0058] Wherein a1 , a2, a3, a4, a5, a6, a7, a8, a9, a10 are indicative of the intensity at corresponding wavelengths.

[0059] If the contributions of the first and second LEDs (operating at two distinct predetermined wavelengths) were also considered, one would obtain: X’=[a1 , a2, a3, a4, a5, a6+b1 , a7, a8+b2, a9, a10] In this situation, if an object were to pass in the predetermined zone 200, a drastic reduction in the components b1 and b2 would be obtained. In this manner, the system would be able to detect the passage of an object. This situation is shown, for example, in figure 3 which shows the same parameters as in figure 2 on the y-axis and x-axis. In addition, based on the intensity of the detected peak (or rather its decrease compared to a known / calibration configuration), an analysis of translucency may also be performed (from which specific properties of the product can be derived).

[0060] In the example in figures 2 and 3, the contributions of both the first and second LEDs 321 , 322 are shown (corresponding, respectively, to the peak on the left and right in figure 2 and to the two peaks more to the right in figure 3). In order to acquire information regarding the passage of a product in said zone 200 or to determine a property of a product passing through said zone 200, the first LED 321 could also be sufficient on its own. The presence of the second LED 322 (or also of any other LEDs as backlighting) makes it possible to have greater information regarding the products passing through, given that the comparison of wavelengths provides additional information.

[0061] For example, if two different types of products (e.g. apricots with two different degrees of drying) are passing along the conveyor line 2, the use of LEDs having different wavelengths would make it possible to have better feedback. For example, every LED could have a wavelength calibrated so as to highlight in particular the passage of a certain type of product. Moreover, by turning the first LED or the second LED 321 , 322 on or off one could configure the system 1 to highlight in particular the passage of certain types of products rather than others.

[0062] Reference has previously been made to a known configuration. Advantageously, the known configuration can be a configuration in which at least the first LED 321 is lit and no product is passing through (see the line indicated as A in figure 2). Advantageously, the front lighting means can also be lit, as in the case indicated by A in figure 4. Advantageously, figure 4 also shows the spectrum with the backlighting means 32 off and the front lighting means 31 on (see the line indicated by B in figure 4) and the spectrum with the backlighting means 32 off and the front lighting means 31 off (see the lines indicated by C in figure 4). The determination of these spectra aids in evaluating the translucency of a product since it makes it possible to have greater information tied to the attenuation of the peak associated with the line A.

[0063] Figure 5 reproduces figure 4, to which the spectra tied to the passage, in the zone 200, of products having two different degrees of transparency have been added as dotted and dash-dotted lines. It may be noted that the peak associated with the lighting up of the first LED 321 is attenuated (see lines E and F).

[0064] The present invention achieves important advantages.

[0065] Firstly, it allows for improving and speeding up the gathering of information regarding products passing through.

[0066] The invention thus conceived is susceptible of numerous modifications and variants, all falling within the scope of the inventive concept that characterises it. Moreover, all the details may be replaced by other technically equivalent elements. All the materials used, as well the dimensions, may in practice be any whatsoever according to needs.

Claims

CLAIMS1 . A product inspection system comprising: i) a product conveyor line (2); ii) an inspection means (3) for inspecting products positioned along the conveyor line (2); said inspection means (3) comprising:- a front lighting means (31 ) for frontally illuminating the products; said front lighting means (31 ) emitting electromagnetic waves of a different wavelength;- a backlighting means (32) for illuminating the products from behind;- a hyperspectral camera (33) that acquires information during the passage of the products; characterised in that the front lighting means (31 ) comprises a light source other than an LED; the backlighting means (32) comprises at least a first LED (321 ) which emits light at a predetermined wavelength.

2. The system according to claim 1 , characterised in that the front lighting means (31 ) for frontally illuminating the products comprises at least one halogen lamp (310) or at least one laser which emits light comprising a plurality of wavelengths.

3. The system according to claim 1 or 2, characterised in that the hyperspectral camera (33) is on the vertical of said first LED (321 ).

4. The system according to any one of the preceding claims, characterised in that the conveyor line (2) comprises a conveyor belt (20) which defines an upper product conveyance section (21 ); the front lighting means (31 ) being located at a greater height than said conveyor belt (20); said first LED (321 ) being located below said upper section (21 ) .

5. The system according to any one of the preceding claims, characterised in that the backlighting means (32) comprises a second LED (322) which emits light at a predetermined wavelength differing from that of the light emitted by the first LED (321 ).

6. The system according to claim 5, characterised in that said second LED (322) is positioned side by side with the first LED (321 ).

7. The system according to any one of the preceding claims, characterised in that it comprises a data analysis means (4) for analysing the data acquired by said hyperspectral camera (33).

8. The system according to any one of the preceding claims, characterised in that among the electromagnetic waves emitted by said front lighting means (31 ) there is also a wavelength equal to that of the light emitted by the first LED (321 ).

9. A product inspection method comprising the steps of: i) conveying the products along a conveyor line (2); ii) analysing the products located along the conveyor line (2) through an inspection means (3); the step of analysing the products comprises the steps of:-frontally illuminating the products by means of electromagnetic waves having a plurality of wavelengths without the use of LEDs;-backlighting the products by means of at least a first LED (321 );-acquiring, by means of a hyperspectral camera (33), information relating to the products during the passage thereof in a predetermined zone (200) of the conveyor line (2).

10. The method according to claim 9, characterised in that it comprises a step of processing the information acquired with the hyperspectral camera (33) to determine whether or not one of the products has passed through said zone (200) or to determine a property of one of the products positioned in said zone (200); said step of determining whether or not one of the products has passed through said zone (200) or of determining a property of one of the products in said zone (200) comprises the steps of:- determining, in a configuration in which one of the products does not pass through said zone (200), a first spectrum at least at the predetermined wavelength emitted by the first LED (321 );- detecting, in a configuration in which one of the products passes throughsaid zone (200), a second spectrum at least at the predetermined wavelength emitted by the first LED (321 );- comparing the first and second spectra at the predetermined wavelength emitted by the first LED (321 ).

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