DE102008052248B4 - Method and device for checking lens structures - Google Patents

Abstract

Test method for checking a lens structure (14) of a lens raster (18) arranged on a surface of a transparent layer (17) of a data carrier (13) for generating a tilt image during data carrier production for quality and / or functionality control of the lens structure (14) characterized by the following steps: - illuminating (2) a surface section of the lenticular grid (18) with at least one illumination source (10) in a first angle (12) to the orthogonal (19) of the surface; - observing (3) a first image (22, 24, 26) of the illuminated surface section with at least one optical detection unit (16) at the same first angle (12); - observing (4) a second image (21, 23, 25) of the illuminated surface section with the optical detection unit (16 ') at a second angle (12') corresponding to the first angle (12) mirrored at the orthogonal (19) or at the first angle (12), provided that the illumination source (10) is arranged at the second angle (12 ') for this purpose; Comparing (5) the first and second images (22, 24, 26, 21, 23, 25) for differences in image brightness; and - with regard to the lens structure (14) of defective data carrier sub-products from further data carrier production.

Description

The invention relates to a test method and to a test device for checking lens structures of a lens grid arranged on a surface of a transparent layer of a data carrier for producing a tilt image, according to the preambles of patent claims 1 and 8.

Data carriers are known, for example in the form of personalization documents, such as identity cards, passports, credit cards, bank cards, cash cards and the like, which increasingly have security features in order to avoid counterfeiting of these documents. By way of example, a paper substrate is provided with a laminating film, wherein the laminating film designed as a plastic layer additionally has a lenticular grid in order to obtain a tilted image and possibly also a three-dimensional spatial impression by the lenticular effect obtained thereby. This avoids merely photographing the underlying personalization data applied to the paper substrate and the remaining pictorial and color designs of the personalization document. As a result, such personalization documents against counterfeiting and falsification are additionally protected.

A method for producing such personalization documents is described in DE 297 004 A and DE 36 34 865 A described. In this case, personal data are written by means of a laser beam in the already completed, laminated card. The card consists of a card inset that is enclosed between transparent cover layers. The labeling process takes place through the transparent cover film. Thus, on the one hand, the production can be significantly simplified, inter alia, after the personalization no further manufacturing steps are required, and on the other hand, the counterfeiting and tampering security are increased because, for example, the data caused by the laser beam material destruction in a no longer changeable form available.

With a suitable choice of the laser intensity can be achieved at the same time with the inscription of the inlets a congruent marking in the volume of the cover sheet up to the surface. In addition, the cover film surface may have a relief structure or a lens structure, which can also be tested manually in a simple manner. It thus represents an authenticity feature and thus hampers to a great extent any manipulation or the attempt to imitate such a card by imitation counterfeiting.

Conventionally, the laser beams in the mostly cylindrically shaped lens structure, each of which is a semicircular cylinder in cross-section, which are deposited on the surface of such a plastic layer, are struck by the laser beam at a certain angle to thereby give the tilt image effect receive. For this, it is important that the incident light beam of the laser is oriented to strike a common focal point of light within the lens structure such that a sharp typeface on the underlying substrate, such as a paper substrate, is ensured. As a result, a viewer who views the underlying typeface at the same angle as the tilt image effect sees the typeface with the necessary sharpness, whereas when viewed from another angle, the incident light does not hit a baring focal point or focus thus scattered. This will give a blurred image.

To check such lens structures, which are required to provide a tamper-proof personalization document, the personalization documents already treated with the laser have been checked for their quality after the inscription of the underlying substrate by viewing those in the respective angle, that the Typeface was checked for sharpness. As a result, when a defective lens structure of the lens raster is found, personalization of the personalization document has already taken place by means of the laser beam and thus this personalization document has been destroyed and a similar document has to be produced again. This reduces the throughput of a personalization document making machine.

From the EP 0 219 012 A2 For example, an end-control method for checking lens structures of a lenticular image frame is known. This lenticular grid is arranged on the surface of a transparent layer of a finished data carrier. Further state of the art show the DE 20 2005 018 964 U1 and the US 5,933,228 A ,

Accordingly, it is the object of the present invention to provide a method and a device for checking lens structures of a lens raster for data carriers, which permit rapid checking during or prior to application of data to the data carrier.

This object is procedurally by the features of claim 1 and Device side solved by the features of claim 8.

The core idea of the invention is that, in a test method for checking lens structures of a lens grid arranged on a surface of a transparent layer of a data carrier to generate a tilt image, the steps defined in claim 1 are applied.

Such a method according to the invention and such a device according to the invention make it possible, without the prior recognition of image sharpness or the sharpness of a typeface after application of the same on the data carrier, before the application of such typefaces and other pictorial components as well as given Color components can be a review of the lens structures on their accuracy within the structure and on the surface. Because it is possible on the basis of the differences in image brightness that the tilting image can be tested for its functioning.

Insofar as the first image is observed from the same direction as the illumination, which is a superimposed state, it is determined that a high image brightness value in the optical detection unit, which can also represent a human eye, arrives with the necessary sharp outlines , a bundling of the incident light beams from the illumination unit within the lens structure takes place at a common collection point and / or focal point and causes the light to fall out again in the same direction. This causes the tilt image effect, namely that only at a certain angle, the underlying typeface or picture can be seen schart. By contrast, in the hidden state, that is to say when the optical detection unit, which can also be in the form of a human eye, is arranged at an angle which is inverse to the orthogonal, the light from the illumination unit must not arrive there as incident light. On the contrary, an inverse state of this surface unit must be created in terms of its image brightness, ie a dark surface and no bright surface, as in the superimposed state, are reproduced. The greater the difference between the dark and the light surface, the defect-free is the lens structure and thus allows a conclusion on the quality of the operation of the lens structure and thus the tilting image.

In contrast to the previous verification method, there will be no need for the test method according to the invention to have previously provided the data carrier with personalization data or other data by means of printing technology or laser marking. Thus, such a check can already be made prior to applying the personalization data or other data to the data carrier or even during the application. This allows during the production of data within a machine for the production of personalization documents already a quality and / or functionality control of the lens structure and thus the lens raster. Faulty partial products with regard to the lens structure are thus excluded from the further personalization document production method and thus allow an unnecessary subsequent sorting out of the completely produced personalization document and thus a cost-effective production of such data carriers, in particular personalization documents. Likewise, such a test method can serve as incoming goods inspection method when plastic layers with the lens structure arranged thereon are in the form of a lenticular grid.

The measurement results obtained therefrom, which are measured by means of the optical detection unit, can be directly compared and evaluated with one another. It is also possible to carry out an evaluation in such a way that first a plurality of lens structures are measured in order to store the image brightness values required as reference values and then to compare this with image brightness values of new lens grids to be checked and their lens structures. Likewise or alternatively, a stored reference value for the image brightness value can serve for comparison purposes, in order to enable a sorting out of plastic layers with a defective lens structure. For this purpose, the additional step of evaluating the differences in the image brightness by means of predeterminable image brightness values, which are compared with the image brightness value of the first and second image, is present. The device according to the invention has a correspondingly designed evaluation unit for this purpose.

A further advantage of the invention lies in the fact that the measurements for checking the lens structure are not influenced by underlying information or printed or laser-inscribed information applied to the surface and thus an objective verification of the lens structure is possible.

According to a preferred embodiment, before taking the observation steps, the method according to the invention comprises the step of predetermining the first angle, in which a maximum brightness value of the image is obtained in the tilt image and the step of predetermining the second angle, in which a minimum brightness value of the Image is obtained on. Accordingly, it is determined for the displayed light, ie for the displayed state, at which illumination angle the maximum brightness of the irradiated area detail can be detected. Likewise, that illumination angle is determined when the light is hidden, that is to say in the blanked-out state, in which a minimum brightness value can be obtained. These expected brightness values serve as reference values in order to compare them with the brightness values of the first and second observed image and thus determine a lens defect freedom in the presence of identical or similar image brightness or a lens defect at different image brightness values.

For the predetermining of the first and second angles, a determination unit may be provided in the device according to the invention.

Further advantageous embodiments will become apparent from the dependent claims.

Advantages and expediencies can be found in the following description in conjunction with the drawing. Hereby show:

1a , b is a flow chart of the method according to the invention;

2a , b, c, d in a schematic representation of a device according to the invention for carrying out the method according to the invention for the superimposed and the suppressed state;

3a , b, c detected images or observed images for the superimposed and hidden state, as obtained by the inventive method;

4 in a diagram, the course of the brightness values as a function of the illumination angles in plastic layers with different lens structures in the displayed state;

5 in a diagram, the course of the image brightness values as a function of the illumination angles at different lens structures in the hidden state;

6 in a diagram compared image brightness values of the first and second image, as in 3 shown; and

7a , b is a comparative representation of the images of a lens structure with and without defect.

In 1a , B is shown in a flow chart, the inventive method. In one step 1 Finds a predetermination of the angles at which maximum and minimum brightness values arise depending on a hidden and a faded in state.

In one step 2 the illumination of the lens grid or the lens structure takes place at the first angle. In one step 3 the brightness of the first image is observed at a first angle. step 4 shows the observation of the second image at a second angle. step 5 leads to a comparison of the measured brightness values of the first and the second image. Thereupon takes place in step 6 an evaluation of the comparison data with predeterminable brightness values instead. In one step 7 the determination takes place as to whether a lens structure is present or not.

In 2 is a schematic representation of the inventive device for performing the method according to the invention in the displayed state and in the hidden state reproduced. In this case, the state is indicated with the state in which an optical detection unit is arranged at the same angle as the one illumination unit. The hidden state, on the other hand, shows the state in which an optical detection unit is arranged in a mirrored or inverse angle with respect to an orthogonal of the surface to the angle of the illumination unit.

The under 2 B shown hidden state differs accordingly from the under 2a shown only in the fact that the optical detection unit 16 ' at an angle 12 ' from -15 ° and not at an angle 12 of + 15 °, like the lighting unit 10 is arranged.

The lighting unit 10 emits at least one light beam 11 that with the angle 12 with respect to an orthogonal 19 perpendicular to the surface of a plastic layer 17 a volume 13 is arranged on a lens structure 14 with several semicircular and cylindrical lenses. The lens structure takes in this case, for example, a surface 18 on the surface of the plastic layer 17 one.

In the displayed state, the optical detection unit detects 16 a failed light beam in the same direction as the incident light beam and receives a first image with a high brightness value, unless the lens structure is defective. In the hidden state, however, is a failing light beam 15 in the optical detection unit 16 ' detected with low image brightness values.

In 2c is the displayed state, as in 2a shown shown. In 2d a hidden state is shown, different from the one in 2 B shown hidden state characterized differs that not the detection unit 16 ' but the lighting unit 10 at an angle 12 ' is arranged from -15 °.

In 3a . 3b and 3c are various image recordings, as they can be obtained by the device and the inventive method, reproduced. The left-hand column shows the hidden state and the right-hand column the superimposed state. A card substrate material having a plastic layer thereon 21 The environment forms an illuminated surface section, which is created by means of the illumination unit 10 with an angle, as below 2 is shown illuminated.

In 3a the two images, ie the first and the second image, are reproduced for a defect-free lens structure. In the right column is a surface section 22 reproduced with a high image brightness value. In the left column, ie for the hidden state, is the same surface section 20 represented with an opposite image brightness value, that is, a very dark area. As a result, the difference between the first picture 22 and the second picture 20 very big in its image brightness. For such a high difference in image brightness, as in 6 under 1a is reproduced, a good quality of the lens structure is determined by the evaluation.

In 3b is the surface section in the displayed state 24 and in the hidden state, the surface section 23 have been detected with image brightness values already having a smaller difference. This is a lens structure of mediocre quality. This indicates a mediocre working tilting image. This smaller difference is reflected in 6 under 1b ,

In 3c are the two surface sections 26 and 25 have been detected for the faded in and out of the state with image brightness values such that these image brightness values have virtually no difference. This slight difference is in 6 under 1c played. Such a small difference in the image brightness of the surface cutouts in the faded-in and faded-out state determined by means of the evaluation unit means that plastic layers having such lens structures are immediately excluded from the further process, since this is a non-functioning lens structure and thus a non-functioning tilt image ,

In 4 In a diagram, the brightness values are shown as a function of different illumination angles. In this case, light from an illumination unit falls at different angles onto the lens structure in the inserted state and, given a functioning tilt image structure, should lead to a maximum brightness value being able to be determined at a specific angle. Advantageously, such a pre-determining step of the maximum brightness value may be performed at a certain angle prior to the actual observation steps to thereby provide reference values with respect to. Brightness values of the image brightness values of the first image to be detected and, with reference to FIG 5 to get the second picture.

In 4 is in the displayed state, a plurality of differently formed lens structures at different illumination angles in terms of brightness has been measured. It has been found that due to the different lens structures, their brightness values as curves 30 . 31 and 32 are shown at different illumination angles their maximum brightness values 30a . 31a and 32a exhibit. Advantageously, in the lens structure to be subsequently observed, these illumination angles, at which the brightness values maximum exist, are used both for the observation and for the illumination for carrying out the method according to the invention.

In 5 are also in a graph, the brightness values on the illumination angle for a hidden state, ie for the hidden light reproduced. This means that for a non-defective lens structure, a brightness value minimum 33a . 34a and 35a must be measured at a certain illumination angle, if the optical detection unit is arranged in the mirrored to the orthogonal inverse angle, as already described above.

6 shows in a diagram compared image brightness values of the first and second image, as in FIG 3a , b and c shown. The determination of the brightness values takes place by means of the detection unit, with 0% corresponding to a dark or black area and 100% to a light or white area respectively at the first and the second angle.

In the diagram, the dark bar corresponds to those image brightness values which have been obtained in a superimposed state, that is, in a state in which the illuminating angle and the viewing angle are identical. The white bar corresponds to those image brightness values which have been obtained at different illumination and viewing angles, that is to say in the blanked state, in which the size of the illumination angle and the viewing angle are identical, but with respect to the orthogonal, different signs +/-; exhibit.

A first possibility of evaluating these measurement results is that in each case a reference value for the displayed and the hidden state 36 . 37 is determined. The lens structure of the lens grid is judged to be functional if, in the displayed state, the measured value is greater than or equal to the first reference value and / or in the blanked state, the measured value is less than or equal to the second reference value 37 is. Another possibility of the evaluation is that as a reference value, a delta 38 between the displayed and the hidden state. The lens structure is then judged to be functional if a measured delta of the two measured values is greater than or equal to the reference value delta.

In 7a and 7b First and second images are reproduced with larger surface sections that have been illuminated and measured. In 7a In the right-hand column, the first image for the displayed state is shown. The left column shows the second image for the hidden state. It can be a nearly defect-free lens structure due to the high brightness differences detect.

In 7b For example, in the right-hand column for the faded-in state, the first image for a defective lens structure is shown, and in the left column, the second image in the faded-out state is also displayed for a defective lens structure. A comparison of these two in 7b reproduced images show that no evenly distributed brightness values are present within the area cutout and thus irregularities in the lens structure must be present. This in turn leads to a smaller difference in the brightness values and thus to the result that a defective lens structure must be present.

LIST OF REFERENCE NUMBERS

1

Step of predetermining

2

light

3, 4

Observe

5

to compare

6

Evaluate

10

lighting source

12

first angle

12 '

second angle

13

disk

14

lens structures

16, 16 '

optical detection unit

17

transparent layer

18

lenticular

19

orthogonal

21, 23, 25

second picture

22, 24, 26

first picture

30-35

Image brightness values

30a, 31a, 32a

maximum brightness value

33a, 34a, 35a

minimum brightness value

36, 37, 38

reference value

Claims (10)

Test method for checking a lens structure ( 14 ) one on a surface of a transparent layer ( 17 ) of a data carrier ( 13 ) arranged lenticular grid ( 18 ) for generating a tilt image during the production of the data carrier, for quality and / or functionality control of the lens structure ( 14 ), characterized by the following steps: - lighting ( 2 ) of a surface section of the lenticular grid ( 18 ) with at least one illumination source ( 10 ) in one to the orthogonal ( 19 ) of the surface first angle ( 12 ); - Observe ( 3 ) of a first image ( 22 . 24 . 26 ) of the illuminated surface section with at least one optical detection unit ( 16 ) in the same first angle ( 12 ); - Observe ( 4 ) of a second image ( 21 . 23 . 25 ) of the illuminated surface section with the optical detection unit ( 16 ' ) at a second angle ( 12 ' ) at the orthogonal ( 19 ) mirrored first angle ( 12 ) or at the first angle ( 12 ), provided that the illumination source ( 10 ) in the second angle ( 12 ' ) is arranged; - To compare ( 5 ) of the first and second images ( 22 . 24 . 26 ; 21 . 23 . 25 ) with respect to differences in image brightness; and - excluding the lens structure ( 14 ) erroneous data carrier sub-products from the further data carrier production. Method according to claim 1, characterized by the step of evaluating ( 6 ) of the differences in the image brightness by means of predeterminable image brightness values ( 30 - 35 ) with the image brightness values of the first and second images ( 22 . 24 . 26 ; 21 . 23 . 25 ). Method according to claim 1 or 2, characterized by the step of predetermining ( 1 ) of the first angle ( 12 ), in which in the tilting image a maximum brightness value ( 30a . 31a . 32a ) of the image will be obtained. Method according to one of the preceding claims, characterized by the step of predetermining ( 1 ) of the second angle ( 12 ' ), in which in the tilting image a minimum brightness value ( 33a . 34a . 35a ) of the image will be obtained. Method according to one of the preceding claims, characterized in that the above steps before application or during the application of personalization or other data on the data carrier ( 13 ) respectively. Method according to one of the preceding claims, characterized in that the obtained first and second images ( 22 . 24 . 26 ; 21 . 23 . 25 ) are evaluated such that first a plurality of lens structures ( 14 ) is measured in order to store the required image brightness values as reference values and these are then compared with image brightness values of new lens grids to be checked ( 18 ) and their lens structures ( 14 ) to compare. Method according to one of the preceding claims, characterized in that a stored reference value for the image brightness values serves as a comparison, wherein the additional step of evaluating the differences in the image brightness by means of predeterminable image brightness values corresponding to the image brightness value of the first and second images ( 22 . 24 . 26 ; 21 . 23 . 25 ) is executed. Inspection device for the inspection of lens structures ( 14 ) one on a surface of a transparent layer ( 17 ) of a data carrier ( 13 ) arranged lenticular grid ( 18 ) for generating a tilting image, characterized by - at least one illumination source ( 10 ) for illuminating the lens grid ( 18 ) in one to the orthogonal ( 19 ) of the surface first angle ( 12 ); An optical detection unit ( 16 ) for observing a first image ( 22 . 24 . 26 ) of the illuminated surface section at the same first angle ( 12 ); The optical detection unit ( 16 ' ) for watching a second image ( 21 . 23 . 25 ) of the illuminated surface section at a second angle ( 12 ' ) at the orthogonal ( 19 ) mirrored first angle ( 12 ) or at the first angle ( 12 ), provided that the illumination source ( 10 ) in the second angle ( 12 ' ), - a comparison unit for comparing the first and second images ( 22 . 24 . 26 ; 21 . 23 . 25 ) with regard to differences in the image brightness, and - an exclusion unit for excluding the lens structure ( 14 ) erroneous data carrier sub-products from the further data carrier production. Apparatus according to claim 8, characterized by an evaluation unit for evaluating the differences in the image brightness by means of predeterminable image brightness values ( 30 - 35 ) with the image brightness values of the first and second images ( 22 . 24 . 26 ; 21 . 23 . 25 ) are comparable. Apparatus according to claim 8 or 9, characterized by a determination unit for predetermining the first angle ( 12 ), in which in the tilting image a maximum brightness value ( 30a . 31a . 32a ) of the image and predetermining the second angle ( 12 ' ), in which in the tilting image a minimum brightness value ( 33a . 34a . 35a ) of the image will be producible.

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