DE102014225775B4 - Method and device for testing a correct adhesive application - Google Patents

Abstract

Device (1) for checking the correctness of an adhesive application (4) on a sample (3)
a radiation source (20) for irradiating the sample (3) on which the surface of the adhesive application (4) is applied, with electromagnetic radiation in the infrared wavelength range and
an image acquisition device (30) for detecting at least one image of the sample (3) in the infrared wavelength region and
an evaluation device which examines the at least one image for inhomogeneities in order thereby to detect defects in the adhesive application (4) on the sample (3),
characterized in that the radiation source (20) and image acquisition device (30) are arranged relative to each other and relative to the sample (3) with the adhesive application (4), that the image acquisition device (30) from the sample (3) or the adhesive application applied thereto (3) 4) detects reflected radiation of the radiation source (20).

Description

The invention relates to a device and a method for checking a correctness of an adhesive application on a sample, in particular a plastic-based laminate semifinished product for a value and / or security document.

In the field of value and / or security documents, it is customary to produce semi-finished products which are assembled from several layers in a lamination process. In this case, similar or different layers can be connected to each other to the document body semi-finished product. Further, such document body semi-finished products typically include a variety of security features and security features that are intended to make it impossible or impossible to forge, falsify, or duplicate the final security or value document, and provide a means of verifying the authenticity of the final security and / or value document or allow the authenticity of information and information stored in the value and / or security document.

Particularly preferred embodiments of such a security document semifinished product are produced, for example, on the basis of a plurality of similar plastic layers, for example based on polycarbonate. In addition, microchips with antenna structures, microlenses and printed or laser-beam-introduced information can be stored and designed in such a document-body semifinished product.

One set of security documents comprises document bodies made on the basis of such a document body semifinished product and advanced to the document body of the security document by applying a hologram film to the document body semifinished product, preferably to an entire surface. To accomplish this, an adhesive, such as an acrylic-based adhesive, is used. In addition to the already finished hologram film, an additional outer protective layer is then usually applied, which can be formed, for example, in the form of a hardcoat.

For the functionality and durability of the finished document body, which itself may be the security document or used as a data card such as a passport, it is important that the hologram film not be peeled or detached from the document body stock in use of the document body. Therefore, it is necessary that the adhesive used for bonding the surface of the document body semifinished product and the hologram film is applied over the entire surface evenly on the surface of the document body semifinished product and alternatively on the surface of the hologram film or alternatively alternatively on both surfaces, and thus no gaps and also has no contamination by contaminants such as dust particles or the like.

In the DE 10 2009 021 677 A1 For example, a method of determining a degree of cure of a coating on a substrate is described. The method comprises: contacting the coating during a first time period with a first material containing a detection substance. Determining a characteristic size which depends on the amount or concentration of the analyte penetrated into the coating during the period, and deriving the degree of cure of the coating from the characteristic size determined in the preceding step.

From the DE 10 2013 216 424 A1 a method for the segmentation of a coating on a substrate is known, wherein light is coupled into a beam splitter and the light is directed to the substrate surface to be inspected, wherein the back-reflected light passes through the beam splitter and is detected by a Bildauswertesystem. Furthermore, a device for carrying out the method is described, in particular an image evaluation system with a recording device. It is thereby provided that the coupled-in light is projected onto the substrate surface as a fringe pattern, the fringe pattern is displaced laterally relative to the substrate surface during an evaluation phase, and a maximum amplitude is determined for each pixel during the displacement and an experimenter image is generated with the maximum amplitude for each pixel. This ensures a stable and clear segmentation of coatings on substrates, which is particularly advantageous in the case of conductive adhesive surfaces on ceramic substrates. By a clear detection of excess conductive adhesive residues, for example, short circuits between traces or conductive adhesive pads can be avoided.

From the prior art it is known to examine layers and also workpieces by means of thermographic methods. For example, this describes US 2001/0050772 A1 a device for non-contact testing of structural and surface defects of a flat structure, such as a tile, wherein in a gap between two transport means, a heat source is arranged, which extends transversely to the transport direction and heated along a line transverse to the transport direction, the flat workpiece to be examined. In Transport direction behind the heat source, a so-called thermographic camera is arranged, which captures a previously heated, cooling area of the workpiece imaging. Structures found in the thermal imaging are indicative of defects in the surface or interior of the workpiece as they hinder and / or prevent uniform heat dissipation at the surface and in the workpiece.

From the US 2011/0189379 A1 is a method for the thermographic examination of non-metallic surfaces, in particular coated non-metallic materials known. The method comprises heating at least a portion of the surface of the non-metallic material, preferably a portion of the surface provided with a non-metallic coating, by means of a short energy pulse, in particular a light pulse or by means of a periodic supply of energy and recording the temporal and spatial temperature profile for at least a plurality of consecutive times. In this embodiment, the thermal decay behavior and / or heating behavior of the workpiece is examined to find defects and structures.

The WO 02/44700 A1 describes a thermographic examination system having a radiation source adjacent to a tissue, for example a paper web for cigarette paper. Downstream of the radiation source in the transport direction of the paper tissue, a sensor is arranged, which detects the heat of the tissue in a spatially resolved manner. Gum strips applied to the paper can be clearly seen.

In the preparation of security documents, even when the adhesive is applied at an elevated temperature, the amounts of adhesive applied are so low that thermal relaxation occurs so rapidly that the prior art methods are not applicable.

The invention is therefore based on the technical object of providing a novel examination method and a novel examination device which make it possible to reliably test adhesive layers of a few micrometres, in particular on plastic laminates, for defects such as gaps and / or soiling.

Basic idea of the invention

The invention is based on the idea not to use the thermal relaxation for finding defects, but to exploit a difference in the reflectivity of the adhesive and the surface of the underlying workpiece, in particular security document body semi-finished product. Since a security document body semifinished product, which is laminated from at least partially transparent plastic layers, usually a variety of each changing markers in the form of printed characters and symbols, or by means of a laser beam inscribed information in the form of material blackening, etc., separate optical detection methods in visible wavelength range. Since these intended for optical visualization markings in the long-wave infrared wavelength range almost do not affect the optical properties, the reflection of light in the infrared wavelength range is used.

definitions

A security document is any document that includes at least one feature that at least complicates or prevents falsification, unauthorized duplication, imitation, or the like. A feature serving this purpose is called a security feature. A physical embodiment of a security feature is referred to as a security element. According to this definition, every security document is also a security element.

Security documents embodying a value are also referred to as value documents. A distinction between value and security documents is not essential to the present invention.

Infrared radiation is radiation outside the visible wavelength range, that is to say at wavelengths greater than 800 nm.

A lamination body is understood to mean a body composed of several layers, which is shaped in a lamination process, preferably in a high-pressure high-pressure lamination process.

A security document body semifinished product is a semi-finished product for producing a security document body, for example a laminate of a plurality of substrate layers, on or in which a plurality of security features and security elements are already integrated or formed therein. A security document body is a self-contained security document or a component of a security document, for example in the form of a data card for a book-type security document, in which the document body is integrated as a page.

An adhesive application is an adhesive layer applied to a surface of a sample. A sample is a flat counterimage on one surface of which an adhesive coating is checked for the presence of defects.

A defect of the adhesive coating is a defect in the adhesive application, i. a deviation from the nominal state of the adhesive application.

A defect may be a gap in the adhesive application where no adhesive or very little adhesive is placed on the sample. A defect may also be an impurity in the adhesive application or the like.

Preferred embodiments

In particular, a device for checking the correctness of an adhesive application on a sample is proposed, which comprises: a radiation source for irradiating the sample on which surface the adhesive application is applied, with electromagnetic radiation in the infrared wavelength range and an imaging device for detecting at least one image of the sample in FIG infrared wavelength range and an evaluation, which examines the at least one image for inhomogeneities to detect defects in the adhesive application on the sample, it being provided that the radiation source and the image-detecting device to each other and arranged relative to the sample with the adhesive coating in that the imaging detection means detects radiation of the radiation source reflected from the sample or the adhesive applied thereto.

Furthermore, a method is provided for checking the correctness of a surface adhesive application on a sample, comprising the steps of: irradiating the sample, on which surface the adhesive application is applied, with electromagnetic radiation in the infrared wavelength range; and detecting at least one image of the sample having the adhesive applied thereto in the infrared wavelength region; and evaluating the at least one image for inhomogeneities to thereby detect defects in the adhesive application on the sample, wherein upon detection of the image, the radiation of the radiation source reflected from the sample or the adhesive applied thereto is detected.

The invention has the advantage that different properties of the adhesive and the underlying surface of the sample are exploited with respect to the reflection of radiation in the infrared wavelength range, to thereby in the captured image areas of the surface of the sample, which are provided with the adhesive application, to distinguish from those areas where, for example, no adhesive is applied. For example, in the infrared wavelength range, the surface of a lamination body made of a plurality of polycarbonate layers better reflects infrared light than an acrylic-based adhesive. This is more absorbent for long-wave infrared radiation, so in an image that measures the direct reflection of the incident infrared radiation, areas covered with adhesive have a different intensity than those areas where no adhesive is applied to the surface of the sample.

The method is suitable, in particular for flat and flat samples with a uniform adhesive application, which should preferably be formed over the full area or at least in a continuous area over the entire area. Likewise, the method can of course also be applied to cases in which a freedom from adhesives of certain regions of the surface is required.

The detection of the reflected radiation is thus preferably carried out during the irradiation.

In one embodiment, the radiation source emits constant and unchanged infrared radiation. Particularly in the case of samples having a large extent, for example when applying an adhesive agent to a semifinished product which is in the form of a roll, such an embodiment may be advantageous in which the sample is moved continuously or stepwise under the radiation source and the image acquisition device.

In another embodiment, the infrared radiation is irradiated only temporally pulsed, also while the image is detected. Here, the irradiation time of the infrared radiation may be shorter than the detection period, similar to the conventional photography using a flashlight.

Particularly suitable is a wavelength range between 8 microns to about 12 microns has been shown. In this spectral range, on the one hand, there are clear differences with regard to the reflection properties of adhesives and workpiece surfaces, in particular plastic surface; on the other hand, optical markings intended for visual perception by a human or normal detection with a camera imaging in the visible wavelength range have no influence on the reflection properties in this wavelength range.

In order to allow a particularly precise evaluation, is in a preferred Embodiment provided that the radiation source homogeneously irradiates the sample surface in a footprint area and the image acquisition device detects the footprint or a flat cutout. If the examined surface of the sample on which the adhesive application is located is homogeneously illuminated, then absolute brightness values or even relative brightness values can be compared over the entire image in order to identify defects. On the other hand, if the illumination is not homogenous, and only locally homogeneous, only significant jumps in the intensity or brightness of the captured image can be used to detect defects. In this case, it is then a prerequisite that the inhomogeneities with respect to the radiation used for illumination spatially have variations whose structures are significantly larger than a pixel resolution of the captured image. This means that the fluctuations in small areas are much lower than fluctuations in the intensity due to inhomogeneous illumination over long distances in the illuminated area. At no point should therefore abrupt intensity fluctuations of the light used for illumination occur.

The image acquisition device is preferably an IR camera, particularly preferably a so-called thermographic camera. This is able to detect light of the corresponding long-wave infrared range reliably spatially resolved.

The use of a laser has proved to be particularly advantageous as a radiation source, as this makes it possible to achieve high radiation intensities with low energy coupling by carrying out the radiation supply pulsed. It is understood that the selected radiation intensities are kept so small that neither in the adhesive nor on the surface or within the sample material changes caused by the irradiation of the infrared light.

Other embodiments may provide a cw laser.

Another advantage of using laser radiation is that the light is already polarized available. Namely, in a preferred embodiment, it is provided to take into account polarization effects in the reflection.

This expands the possibility of distinguishing the properties of the adhesive and the sample surface during reflection.

If the radiation source does not generate directly polarized radiation, then in one embodiment this can be brought about via a polarization filter. In order to detect the radiation also polarization-dependent, it is provided in one embodiment that a polarization analyzer is arranged in front of the image acquisition device.

In one embodiment, it is exploited that, for example, the Brewster angle for the adhesive and the surface of the sample differ. For example, if the radiation is irradiated at the Brewster angle for the transition of air or gaseous atmosphere over the adhesive to the adhesive and the polarization chosen so that the electric field vector oscillates in the plane of reflection, under this polarization a minimum of the incident Radiation, preferably no radiation is reflected. Since the Brewster angle is deviating for the atmospheric surface area of the specimen, however, reflection of the light thus polarized takes place there. As a result, the contrast difference between a reflection on the adhesive, for example made of acrylic and the surface of polycarbonate can be increased again.

In addition to defects that are not covered with adhesive, in the acquired images of the reflected infrared radiation, however, areas with a different intensity / brightness, which are caused by impurities in the adhesive, additionally occur. Such dust particles or the like usually have even lower reflectivity than the adhesive, so that the intensity in the images is once again lower than in those areas in which the adhesive is applied to the sample. Thus, contaminants in the adhesive, which may also lead to subsequent delaminations of a manufactured security document, can be reliably detected.

In a preferred embodiment of the invention, the evaluation device is designed such that it classifies the defects found. Thus, places where the adhesive application is completely absent can be classified in one category, while other sites where contaminants are detected can be classified in another class. Furthermore, it is possible that the defects found also according to their geometric shape, e.g. the area and / or illumination, in order to be able to distinguish minimal defects or soiling in the adhesive from those in which adhesives are largely absent or where large-surface soiling is present. Depending on the specific application, it can then be decided which classes of defects are acceptable for further production or are unacceptable.

• 1 eine schematische Darstellung einer Vorrichtung zum Prüfen eines Haftmittelauftrags;
• 2 eine schematische Darstellung einer erfassten Abbildung eines Vierfachnutzens von Dokument-Halbzeugen mit einem flächigen Haftmittelauftrag, welcher entlang einer sinusförmigen Spur entfernt ist;
• 3a eine schematische Ansicht einer erfassten Originalabbildung eines Dokumentkörper-Halbzeugs;
• 3b eine schematische Ansicht der Abbildung nach 3a nach dem Ausführen einer sogenannten Shading-Korrektur;
• 3c Intensitätsprotokoll entlang einer Strecke A-B nach 3b;
• 3d eine Ansicht der Abbildung nach 3a und 3b, in der Fehlstellen nach einer ersten Kategorie hell gekennzeichnet sind;
• 4a eine Originalaufnahme eines mit Haftmittel beschichteten Dokumenten-Halbzeugs;
• 4b das Ergebnis der Auswertung, in der Fehlstellen des Haftmittelauftrags hell gekennzeichnet sind;
• 4c ein Ergebnis der Auswertung der Abbildung nach 4a, in der Verschmutzungen hell gekennzeichnet sind; und
• 5 schematisch ein Ablaufdiagramm eines Verfahrens zum Bestimmen der Korrektheit eines Haftmittelauftrags auf eine Probe.

The invention will be explained in more detail with reference to a drawing. Hereby show:

• 1 a schematic representation of an apparatus for testing an adhesive application;
• 2 a schematic representation of a captured image of a four-time use of document semi-finished products with a surface adhesive coating, which is removed along a sinusoidal track;
• 3a a schematic view of a captured original image of a document body semifinished product;
• 3b a schematic view of the figure 3a after performing a so-called shading correction;
• 3c Intensity log along a route A - B to 3b ;
• 3d a view of the picture 3a and 3b in which blemishes are marked bright after a first category;
• 4a an original photograph of an adhesive-coated semi-finished document;
• 4b the result of the evaluation, in which defects of the adhesive application are marked bright;
• 4c a result of the evaluation of the figure 4a in which soils are brightly marked; and
• 5 schematically a flowchart of a method for determining the correctness of an adhesive application to a sample.

In 1 is schematically a device 1 for checking the correctness of an adhesive application 4 on a sample 3 shown. In the sample 3 it is preferably a semi-finished product for the production of security documents, preferably a laminate. This can be, for example, a multiple use of document body semi-finished products. The sample 3 is preferably extended flat and has a smooth flat surface 7 on top of that the adhesive job 4 is applied. An adhesive 8th is in a thin layer 9 , which is preferably a few microns thick, on the surface 7 the sample 3 applied. As in 1 can be seen, assigns the adhesive agent 4 , which completely the surface 7 to cover, a flaw 5 in the form of a gap 11 on, on which no adhesive 8th on the surface 7 is applied. Further, in the adhesive 8th or the adhesive agent order 4 a defect 5 in the form of an impurity 6 contain.

The sample 3 is on a transport device 2 arranged the sample 3 into a measuring range 15 transported. An at the transport device 2 arranged position sensor 10 recognizes that the sample 3 yourself in the measuring range 15 located. An evaluation and control device 12 , which is a signal from the position sensor 10 receives, activates a measurement process. A radiation source 20 , emits infrared radiation 21 on top 7 the sample 3 or the adhesive agent order 4 , Part of the infrared radiation 21 gets on the surface 7 or the sample 3 a surface 17 of the adhesive agent 4 reflected. This reflected infrared radiation 31 is by an image acquisition device 30 captured to a spatially resolved a footprint 16 or an area-related subarea. The image acquisition device 30 is preferably designed as an infrared camera, for example a thermographic camera.

The irradiated infrared radiation preferably has a wavelength in the range between 8 and 12 microns, more preferably about 10 microns. The radiation source may be formed as a heat radiator, but is particularly preferably designed as a laser, as a result, a high radiation intensity can be achieved. The evaluation and control device 12 controls both the radiation source 20 , as well as the image acquisition device 30 so that it is guaranteed to be on the surface 7 the sample 3 or the surface 17 of the adhesive agent 4 reflected infrared radiation 31 is detected. In a preferred embodiment, the radiation source becomes 20 operated only pulsed and that synchronized so that the imaging device 30 a picture of the footprint 16 or part of it.

In one embodiment it is provided that the surface 7 the sample 3 or the surface 17 of the adhesive agent 4 Illuminated over a large area and also recorded over a large area. In particular, in a device in which the sample 3 is moved continuously, however, a strip-like detection is possible and thus a scanning structure of the surface image of the surface 7 the sample 3 or adhesive agent 4 on the surface 7 the sample 3 , In this case, the image acquisition device then detects a strip of the surface in each case 7 the sample 3 or the surface 17 of the adhesive agent 4 about the infrared radiation reflected in this strip 31 , where the strip is the surface 7 through the infrared radiation 21 from the radiation source 20 is illuminated.

The evaluation and control device 12 is formed, the detected by means of image processing software the sample 3 evaluate.

For example, if the sample is a multi-layered document body blank (a document body preform), which is made of polycarbonate layers, and in the adhesive application to an acrylic adhesive, the reflectivity of the surface of the sample is substantially higher than the reflectivity of the adhesive. Thus, in the captured image, defects where no adhesive is applied appear brighter than areas in which adhesive is applied. In contrast, imperfections in the form of impurities usually have a high absorption, so that their associated pixels in the image have an even lower intensity than areas in which the adhesive is applied.

Exemplary is in 2 a a fourfold benefit 51 shown by security document semi-finished products. On a fourfold is an adhesive over the entire surface 8th applied in the form of an acrylic adhesive, from which a sinusoidal track is scraped off again. It can be clearly seen that a much higher intensity of the detected reflected infrared radiation can be seen in the region of the scratch track in which the adhesive is removed than in the remaining area in which the adhesive is applied.

In 3a is a to see in the about one and a half fourfold 51 . 52 of polycarbonate-based security document semi-finished products having an acrylic adhesive agent coating. Between the fourfold benefits 51 and 52 is an area in which the reflection on a conveyor belt 53 the transport device is detected. Its surface is preferably chosen so that it has a contrast to the adhesive 8th and preferably also opposite the surface of the sample 3 having. In the left quadruple benefit 51 are flaws 54 to recognize in the form of elongated rectangles. It can also be seen that in this not completely optimized device, with which the measurement was carried out, differences in the brightness of the measured in reflection adhesive application occurs. Therefore, a so-called shading correction is performed, which is to reduce for each vertical image sections systematic inhomogeneities caused by the lighting and / or detection.

In 3b the figure is shown after performing this "vertical" shading correction.

In 3c is the signal intensity versus position along a vertical path 60 AB shown as an example after the shading correction. The vertical x-axis 61 indicates the position along the route AB. The horizontal y-axis 62 indicates the intensity in the picture along the distance AB. Good to realize is that in one section 60 along the route, the intensity values after the shading correction have only a small fluctuation. In the area of the defect 54 however, a clearly excessive intensity can be detected, so that a finding of the defects 54 by a pattern recognition software is easily possible.

3d shows a result of the evaluation, in the areas with defects 54 bright against a dark background are marked. The sample edges also appear bright 63 to which no adhesive is applied, but a reflection of the incident infrared radiation takes place.

In 4a is another similar to the post 3a which again shows infrared reflection images of polycarbonate-based document body semifinished products to which an acrylic varnish is applied. In the framed areas 71 . 72 and 73 are flaws 75 in the form of gaps 76 and a pollution 77 to recognize. 4b shows the evaluation result in which the defects 75 (Gaps 76 ), where there is no adhesive coating, are highlighted against the background. 4c on the other hand shows those places where the reflection is less than in the adhesive application and thus the defects 75 which as impurities 77 classified, are highlighted.

In addition to the "simple reflection" of the infrared radiation, it is also possible to exploit polarization effects. For this purpose, the device 1 in one embodiment, a polarizer 22 on. Is the radiation source 20 formed as a laser that already generates polarized infrared radiation, the example polarizer 22 in the form of a polarization filter also missing in the measurement of polarization effects. In one embodiment, the infrared radiation 21 so to the test and the adhesive application 4 that radiated an angle of incidence θ , measured against a surface normal 19 a Brewster angle θ _B the transition of air into the adhesive corresponds. Here, the infrared radiation is irradiated so that an E-field vector 33 vibrates in the reflection plane. Under the Brewster angle θ _B polarized radiation is minimally, ideally not reflected at all. In front of the image acquisition device 30 can be a polarization analyzer 32 are used, which also reflects only radiation 31 lets happen, which is so polarized that the E-field vector 34 vibrates in the reflection plane. The reflection plane is determined by the direction of incidence of the infrared light 21 and the failure direction of the reflected portion 31 established. Because the Brewster angle θ _B for reflection on the surface 7 the sample 3 due to a different refractive index of the material of the sample 3 from the refractive index of the adhesive 8th deviating, finds complete suppression of the reflection on the sample 3 not take place, so that a contrast sharpening effect between Adhesive surfaces and non-adhesive surface areas of the surface 7 occurs.

It is also possible to perform other measurements utilizing the polarization. Thus, for example, unpolarized light can be irradiated in the infrared wavelength range, for example of 10 μm, and the intensity of the light can be measured polarization-analyzed, for example by measuring only that light which is polarized such that the E-field vector 34 vibrates in the reflection plane.

Since the material properties, such as reflectivity and refractive index, etc. are also dependent on the temperature of the materials, the sample can also be tempered with the adhesive as a whole.

In 5 is a schematic flow diagram of a method 100 for determining the correctness of an adhesive application to a sample. A sample provided with an adhesive agent is supplied 101 , The sample is irradiated with infrared radiation in the range between 8 μm and 12 μm 102 and an image of the irradiated sample is detected in a spatially resolved manner on the basis of the infrared radiation reflected on the sample in the corresponding wavelength range 103 , The detection takes place here so that it is detected during the irradiation of the sample. This ensures that reflected radiation is detected and not the thermal radiation emanating from the body.

The captured image is evaluated 104 with respect to the spatially resolved detected intensity. In this case, a so-called shading correction can be performed 105 in order to eliminate inhomogeneities due to the illumination. Subsequently, using a pattern recognition 106 looking for defects. These can be categorized 107. A category of defects can be those where no adhesive agent application is detected. As a rule, these areas have a higher reflectivity and can therefore be recognized by a higher intensity in the acquired IR image. Other defects may be caused by contamination of the adhesive, in the adhesive or on the adhesive. These can usually be recognized by the fact that the reflected intensity is lower than in the area of the correctly applied adhesive. In addition, the different types of defects can also be categorized on the basis of their geometric shape and / or surface. For example, very small defects may be acceptable, while larger ones may be unacceptable. The results of the evaluation are usually via an output device 14 (see. 1 108). This can be done, for example, via a visualization of the defects or alternatively and additionally in the form of a file which contains locations and positions of the defects and, if appropriate, their classification. The results can be used to prevent further processing of the corresponding sample and / or trigger post-processing to eliminate the defects.

It is understood that only exemplary embodiments are described. The features described in the individual embodiments may be combined to form variations of the invention.

LIST OF REFERENCE NUMBERS

1

Device for testing the application of adhesive

2

transport means

3

sample

4

Adhesive application

5

void

6

pollution

7

surface

8th

adhesives

9

layer

10

position sensor

11

Gaps

12

Evaluation and control device

14

output device

15

measuring range

16

footprint

17

Surface of the adhesive application

19

surface normal

20

radiation source

21

irradiated infrared radiation

22

polarizer

30

Picture detector

31

reflected infrared radiation

32

polarization

33

E-field vector

34

E-field vector

35

spatially resolved illustration

51, 52

Fourfold use of document body semi-finished products (samples)

53

conveyor belt

54

defects

60

route

61

X axis

62

y-axis

63

sample edges

71 - 73

areas

75

void

76

gap

77

pollution

100

method

101-108

steps

θ

angle

θ _B

Brewster angle

A, B

positions

Claims (16)

Device (1) for checking a correctness of an adhesive application (4) on a sample (3) comprising a radiation source (20) for irradiating the sample (3) on which the adhesive application (4) is applied on a surface with electromagnetic radiation in the infrared wavelength range and an imaging detection means (30) for detecting at least one image of the sample (3) in the infrared wavelength range, and an evaluation device, which at least one imaging examined for inhomogeneities to thereby detect defects in the adhesive coating (4) on the sample (3), characterized in that the radiation source (20) and image acquisition device (30) are arranged relative to one another and relative to the sample (3) with the adhesive application (4) such that the image acquisition device (30) is in contact with the sample (3) or the adhesive application (4 ) detects reflected radiation of the radiation source (20). Device (1) according to Claim 1 , characterized in that the image is detected during the irradiation. Device (1) according to one of the preceding claims, characterized in that the radiation source (20) emits light in the wavelength range of 8 microns to 12 microns. Device (1) according to one of the preceding claims, characterized in that the radiation source (20) homogeneously irradiates the sample (3) flat in an illumination region and the image acquisition device (30) detects the illumination region or a planar detail. Device (1) according to one of the preceding claims, characterized in that the image acquisition device (30) is an IR camera. Device (1) according to one of the preceding claims, characterized in that the evaluation device executes image processing of the detected at least one image and determines defects in the adhesive application (4) in the respective captured image on the basis of contrast differences and / or brightness / intensity values of the detected pixels whose positions correspond to those locations represented by the corresponding pixels in the captured image. Device (1) according to one of the preceding claims, characterized in that the radiation source (20) emits polarized electromagnetic radiation or is polarized and in front of the image acquisition device (30) a polarization analyzer is arranged. Device (1) according to one of the preceding claims, characterized in that the radiation source (20) is a laser. Device (1) according to one of the preceding claims, characterized in that the radiation is directed onto the sample (3) with the adhesive application (4), so that an angle measured to a surface normal of the surface of the sample (3) the Brewster angle for the air / adhesive interface is equivalent, and the incident light is polarized such that the electric field vector oscillates in the incident reflection plane and the polarization analyzer is oriented to detect reflected light from the image sensing device whose electric field vector is in the incident Reflection level oscillates. Method for checking the correctness of a surface adhesive application (4) on a sample (3), comprising the steps of: irradiating the sample (3), on which surface the adhesive application is applied, with electromagnetic radiation in the infrared wavelength range; and detecting at least one image of the sample (3) having the adhesive coating (4) applied thereto in the infrared wavelength range and evaluating the at least one image for inhomogeneities to thereby detect defects in the adhesive coating (4) on the sample (3) characterized in that the radiation of the radiation source (20) reflected by the sample (3) or the adhesive agent applied thereto (4) is detected when the image is acquired. Method according to Claim 10 , characterized in that from the radiation source (20) Light is emitted in the wavelength range between 8 microns to 12 microns. Method according to one of Claims 10 or 11 , characterized in that on the sample (3) with the adhesive application (4) a footprint is homogeneously illuminated and the entire footprint or a part thereof is detected by the image acquisition device via the reflected radiation. Method according to one of Claims 10 to 12 , characterized in that the radiation is generated polarized. Method according to one of Claims 10 to 13 characterized in that the radiation is radiated at an angle measured to a surface normal of the surface of the sample (3) corresponding to the Brewster angle for the air / adhesive interface, and the irradiated light is polarized such that the electric field vector in the incident-reflection plane vibrates and the polarization analyzer is aligned so that reflected light is detected by the image-detecting device whose electric field vector oscillates in the incident-reflection plane. Method according to one of Claims 10 to 14 , characterized in that deviations in the brightness / intensity detected in the detected at least one image as defects. Method according to one of Claims 10 to 15 , characterized in that detected defects are classified.

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