EP1490840B1 - Device for checking security elements - Google Patents

Abstract

The invention relates to a device ( 20 ) and a method for making visible security elements present in an object ( 4 ) and comprising at least one photoluminescent segment which is characterized by linearly polarized photoluminescence and/or linearly polarized absorption. According to the invention, a good contrast is achieved with few interfering signals, by arranging at least one light source ( 1 ) and at least one polarization filter ( 2 ) in such a way that the light ( 24 ) from the light source ( 1 ) is linearly polarized ( 23 ) by means of the polarization filter ( 2 ) and hits the object ( 4 ) or the photoluminescent segments in said object, and photoluminescent light ( 25 ) from the segments can be observed through another and/or the same polarization filter ( 2 ).

Description

TECHNICAL AREA

The present invention relates to an apparatus and a method for visualizing security elements present in an object, which have at least one photoluminescent segment which is characterized by a linearly polarized photoluminescence and / or linearly polarized absorption.

Such a security element is z. As described in WO 00/19016.

STATE OF THE ART

It is commonly known that for security papers and security articles in general, for example for banknotes, checks, stocks, bonds, identity cards, Passports, driving licenses, tickets, stamps and similar documents or for example for bank cards, credit cards and similar security elements are used, which have the purpose of preventing or complicating the forgery of these objects by unauthorized persons (R. van Renesse, Optical Document Security "(1997 Similarly, such security elements are used to identify the authenticity or validity of objects, or more generally, to facilitate or facilitate the identification of objects.

For example, the use of security threads or strips, which may be, for example, a metal-coated plastic, is widely used in security papers, particularly for use in banknotes and similar securities. For example, if these security threads or strips are embedded in the security paper and subsequently printed at most, these security elements can not be easily recognized when the object is viewed in reflection. But they appear as a dark shadow when the object is illuminated and thus observed in transmission.

In particular, in order to ensure the counterfeit security of security articles, such as security papers, many proposals have been made in recent times to provide security elements with certain properties, so that not only the presence of security elements in and of themselves, but in particular the presence of special Properties which should guarantee the authenticity of the secured object (US 4,897,300, US 5,118,349, US 5,314,739, US 5,388,862, US 5,465,301, DE-A 1,446,851, GB 1,095,286). From DE-A 1, 446,851, for example, a security thread has become known, which has a multi-colored micro-printing; The ink can also be fluorescent. The areas printed with different colors are so small or so close together in this thread that they can not be distinguished by the naked eye and therefore appear to the viewer as a monochrome pattern. The micro-printing and its different colors, however, can be detected by means of a magnifying glass or a microscope.

Furthermore, reference is made to WO 00/19016, in which a security paper or generally safety articles are described, which contain at least one security element having at least one photoluminescent segment, which is characterized by a linearly polarized photoluminescence and / or linearly polarized absorption. In this document, it is pointed out that linearly polarized excitation light, which, for example, by an external light source i. V. m. a linear polarizer can be generated, is absorbed by the segment differently depending on the orientation of the polarization axis of the segment and the polarization direction of the excitation light, which when viewed through the naked eye can lead to a strong light / dark contrast.

Attention is further drawn to US 5,892,239, which describes a device for identifying security features on a security document, in which unpolarized light is radiated in and a polarizer is used in the detection. A similar device describe the US 4,990,790 and DE 19 923 885. Devices with 2 polarizers are described in DE 19 802 781 and US 6,047,964.

In the context of such security features with photoluminescent segments having polarizing properties, there is a need for devices for detecting or verifying such security features. Such devices should have a high resolution and good contrast while technically simple and compact to be realized, that is to be resistant and cheap to produce in order to allow widespread use.

PRESENTATION OF THE INVENTION

It is therefore the object of the invention to provide a method or a device for visualizing security elements present in an object, wherein the security elements to be observed have at least one photoluminescent segment which is characterized by a linearly polarized photoluminescence and / or linearly polarized absorption is. The device is intended to be an easy and reliable detection allow the security elements without having to resort to a complicated and possibly vulnerable construction.

The solution of this object is achieved by a device according to claim 1 and a method according to claim 17.

In other words, the gist of the invention is to send both the incident light and the photoluminescent light from the segment through the same polarizing filter. As a result, the contrast of the observation is increased in a surprisingly simple manner and interference signals, which usually occur as a result of stray light or due to unclean polarization, can be efficiently suppressed. This is especially true if the security elements have linearly polarized photoluminescence and linearly polarized absorption. This arrangement is particularly simple and efficient, since in this case the contrast can be particularly increased and only one polarizing filter is required, which is used for both light paths and which in this case has a polarizing effect in both spectral regions (excitation and photoluminescence).

In this case, the at least one light source emits light in the UV range, and the photoluminescent light from the at least one segment is in the visible range. Such segments are invisible to the naked eye under normal conditions and have a particularly high security with regard to counterfeiting. Especially for such security features, there is a need for specific and simple verification devices.

Preferably, the light source is a UV light source having an emission in the range of 180 to 500 nanometers, typically in the range of 200 up to 400 nanometers. In this case, the original light source does not have to be limited to this frequency range, but it can also be a broadband light source, in front of which a corresponding bandpass filter is arranged, so that only UV light strikes the object, in particular in the stated range. In principle, it is possible in such a choice of a broadband light source of this band filter in such a way that it also acts as a polarizing filter. The arrangement of 2 filters can be avoided. For example, the light source may be a mercury vapor lamp, a laser light source, or a halogen lamp or an arc discharge lamp.

According to a further preferred embodiment of the present invention, the device is designed such that the observation is effected by a filter which does not allow light to pass substantially in the wavelength range of the light source, while light in the wavelength range of the light photoluminescent from the segment can pass substantially unhindered. Since irradiated in the UV region and observed in the visible region, an additional filter should be used for observation, which has substantially no transmission in the UV region, while it is transparent to the visible region. In this way, stray light from the light sources (direct stray light or reflected stray light from housing parts or from the object with the security feature) can be efficiently suppressed and the verification of the security features is improved or improved. be simplified.

Another preferred embodiment is characterized in that the polarization filter for observation about an axis perpendicular to the plane of the polarizing filter can be rotated in particular by means of a motor. The rotation of the polarizing filter results in an intense light / dark effect of the segments (bright when the directions of polarization are parallel, dark when the directions of polarization are perpendicular to each other) during observation, which makes the security features particularly prominent with respect to the environment. It is advisable to use the polarization filter with a Rotation frequency in the range of 0.2 to 5 Hz, particularly preferably to rotate at a rotational frequency of 0.5 to 2 Hz. At such rotation frequencies, the light / dark effect is best seen by the human eye.

Simply the rotation of the polarizing filter can be technically realized by the polarization filter is enclosed in a mounting ring, wherein the polarizing filter is rotated via a running around the socket ring, driven by a motor driven drive belt drive belt, and wherein particularly preferably the socket ring over at least three, tangentially engaging guide rollers is rotatably mounted. In this way, for example, a round polarizing filter can be used, in which case the radiation to some extent from obliquely above laterally through several light sources through the polarizing filter, and the observation of the reflected light through the central region of the polarizing filter can be made vertically upward. This simple observation through the center of the polarizing filter is not possible if the polarizing filter is rotatably supported by a central axis.

According to a further preferred embodiment of the present invention, a camera, especially a CCD color camera, is provided for observation, wherein the image taken by the camera, optionally after appropriate image processing such as contrast adjustment, color matching, brightness adjustment, enlargement and / or resolution adjustment, on a display , particularly preferably a TFT-LCD color display is mapped. The Use of electronic detection means allows sensitive detection and in particular allows optimized with respect to the features to be observed

Image editing. Security features can be detected even better on a corresponding display.

In addition, the camera may preferably be a multi-chip camera, in particular a Dreichip camera. The resolution and thus the quality of the verification of the security feature can be increased by such high-level camera types.

Alternatively or additionally, it is possible to facilitate the observation thereby or to improve that is observed by at least one lens or lens combination, particularly preferably by a magnifying glass.

Another preferred embodiment is characterized in that the light source is a UV lamp, preferably a UV tube having a wavelength in the range of about 200 to about 390 nanometers, more preferably having a wavelength in the range of about 350 to about 370 nanometers (each the maxima of the emission bands), and that the polarization filter is a broadband linear polarizer which is particularly preferably polarizing in a wavelength range of 300 to 770 nanometers. As suitable prove z. For example, mercury vapor UV tubes optionally coated with phosphorus to push the center of the emitted line into the desired range (eg, 370 nanometers). In order for the polarizing filter to have a linear polarizing effect both in the excitation region and in the observation region, this filter should either have a broadband characteristic or be permeable and polarizing at least in the observation region and in the region of the irradiated UV line. It is important to adjust the characteristic of the UV tube to the characteristic of the polarizing filter (or vice versa), d. H. Care must be taken to ensure that the polarization filter achieves efficient linear polarization both in the range of observation (eg in the visible range) and in the UV range of the radiation, and losses in these spectral ranges are kept low.

A further improvement of the device according to the invention can be obtained by additionally providing the device with other other security features. The further security features may include magnetic, electrical, optical, electronic, electro-optical features, for example selected from the group barcodes, magnetic stripes, conductivity, electroluminescence, photoluminescence, up-conversion (anti-stokes), infrared signatures, electronically readable texts ( OCR font) also with infrared writing, X-ray fluorescence characteristics, etc. act.

Further preferred embodiments of the device and the method according to the invention are described in the dependent claims.

BRIEF EXPLANATION OF THE FIGURES

Fig. 1

a) eine perspektivische Ansicht von oben auf ein Handgerät mit elektronischem Display ; b) einen zentralen Schnitt senkrecht zur Hauptachse eines Handgeräts gemäss Fig. 1a) ; c) eine Seitenansicht eines Handgeräts gemäss Fig. 1a) ; d) eine Ansicht von unten auf das Gehäuse-Oberteil gemäss A-A in Fig. 1c) ; e) eine Ansicht von oben auf das Gehäuse-Unterteil gemäss B-B in Fig. 1c) ; und

Fig. 2

einen Schnitt gemäss Fig. 1b) durch einen Handgerät ohne elektronisches Display.

The invention will be explained in more detail with reference to embodiments in conjunction with the drawings. Show it:

Fig. 1

a) a perspective view from above of a handheld device with electronic display; b) a central section perpendicular to the main axis of a hand-held device according to FIG. 1a); c) a side view of a hand-held device according to FIG. 1a); d) a view from below of the housing upper part according to AA in Fig. 1c); e) a view from above of the housing lower part according to BB in Fig. 1c); and

Fig. 2

a section according to FIG. 1b) by a hand-held device without electronic Display.

WAYS FOR CARRYING OUT THE INVENTION

Fig. 1 a) shows a perspective view of a handset 20 with electronic display, which is to serve as a first embodiment of the present invention. The handset 20 has a housing upper part 8 and a housing lower part 10, which are screwed on each other and which both have an oval cross-section. On the upper side 18, a TFT-LCD color display 7 is arranged, on which the object 4 to be examined is imaged. The handset 20 has at the end of the main axis (the ellipse) at half height on grip notches 19, which make the device easier to handle. In addition, ventilation slots 12 are arranged immediately below these notches 19 in order to allow the heat generated in the device to escape. The device has a height of 13.5 cm, a length along the major axis of 23.3 cm and a width along the minor axis of 15.4 cm. The total weight is less than 10 kg.

The device has on the top 18 via two switches 11, wherein one of the switches is provided for switching on the lamps, and the other switch for switching on the motor for the rotation of the polarizing filter 2. In addition, the device has three rotary control 13 in the upper part of long side. These knobs 13 make it possible to adjust the brightness, the contrast and the color sensitivity of the display 7 according to the needs. In addition, connection sockets 14, 15 and 16 are also provided in the region of the longitudinal side. One of these sockets serves as a connector 14 for an external display. In other words, the output of the CCD camera 6 arranged in the interior can be led to another display via this connection socket. Furthermore, two terminals 15 and 16 are provided, one of which serves to connect a battery charger. The power supply of the device in autonomous operation is ensured by accumulators arranged inside the housing, which can be charged via this connection 16. The second plug 15 can be used to connect an external 12 volt supply if either the accumulators are empty or in principle a stationary operation is intended.

Fig. 1b) shows a central section along the minor axis of the ellipsoidal device, which is to serve the schematic representation of the operation. The device has two UV lamps 1, which are arranged laterally in the housing upper part 8 parallel to the main axis. These are lamps whose emission characteristics have a maximum in the range from 365 to 370 nm (UVA, eg mercury vapor lamps with corresponding Phosphor coating or UV LEDs). The light 24 emanating from these lamps passes through a centrally arranged polarizing filter 2, in order then to impinge as a linearly polarized light 23 on the object 4 to be examined with security feature. In this case, security features can be observed, which have a photoluminescence from the UV region in the visible range, and in which either absorption and / or emission are linearly polarized. It can be a variety of objects, such. As banknotes, certificates, tickets, access rights, stamps, ID cards, packaging, identity cards, passports, etc., in general to documents whose fake security should be ensured by appropriate photoluminescent security features with polarizing properties.

The object 4 is covered for viewing by the device resp. covered, and observed through a specially designated hole 27 in the bottom. The lower housing part has over the hole 27 via a dark room 22 a height of about 5.5 cm, which is sealed to the interior 21 in the housing upper part 8 by a cover glass 3. The cover glass 3 is intended to prevent that the cavity 21, in which optical and electronic devices are located, can not be contaminated. The light emitted by the object 4 in the visible range, usually also polarized light 25, which may have a variety of colors according to the security features, then passes up through the same polarizing filter 2 on a CCD camera 6. This CCD camera 6 also has a filter. 5 which eliminates electromagnetic radiation in the frequency range of the light sources 1 from the light entering the camera. In other words, it is a UV filter, which direct light of the UV lamps 1, UV scattered light, or of Housing parts or the object 4 reflected UV light does not enter the CCD camera 6. The CCD camera is connected to a TFT-LCD color display 7 on which the security features of the object 4 are imaged. In this case, the data determined by the CCD camera 6 can optionally be subjected to an adapted image processing, which makes the security features stand out.

The polarizing filter 2 can be rotated in this device for observation. As a result, a characteristic light / dark effect can be observed during observation. The bright / dark effect is achieved by the fact that when the polarization direction of the polarizing filter 2 and the polarization direction of the polarizing segment of the security feature are aligned parallel to each other, a bright reflection appears on the display, while in orthogonal alignment no reflection can be observed. The observation by the same polarization filter leads to an increased visibility of this light / dark effect, since it automatically ensures optimum coordination or adaptation of the polarization direction of irradiation and observation.

The polarization filter is a broadband polarization filter, i. H. a carrier that efficiently polarizes light in the range of about 300 to about 770 nanometers. In question come to z. UV polarizers, such as those available from 3M or marketed by Polaroid under the name HNP'B linear ultraviolet * (275-750 nm as the passband or polarization region, respectively).

Fig. 1c) shows a side view of the device. It can be seen in particular how the lower housing part 10 is fastened via fastening screws 26 on the housing upper part 8.

Fig. 1d) shows a view according to AA in Fig. 1c), ie a view into the housing upper part 8 from below. In this case, the specific arrangement of the light sources 1 with their socket 29, in which the head parts 28 of the light sources 1 are inserted. Furthermore, the arrangement of the rotary control 13 in the housing upper part 8, as well as the switch 11 can be seen.

Fig. 1e) shows a view according to B-B in Fig. 1c), d. H. a view of the housing lower part 10 from above. It can be seen how the polarizing filter 2 is rotatably mounted on the lower part 10. For this purpose, the polarizing filter 2 is enclosed in a mounting ring 30. The mounting ring 30 has on its outer edge an incision in which a drive belt 31 extends. This rubber drive belt 31 is stretched around the socket ring 30 by means of a drive wheel 33. The drive wheel 33 is driven by a mounted on the housing base 10, projecting into the housing upper part 8 motor, whereby the polarizing filter 2 can be rotated. The polarizing filter 2 is mounted on three freely rotatable guide rollers 34, which also engage from the outside in specifically provided, V-shaped flanks of the mounting ring 30. This guidance of the polarizing filter 2 from the outside makes it possible to guide the observation centrally through the center of the filter.

Fig. 2 shows a further embodiment of the present invention, in which the observation is not realized electronically. The section shown in Fig. 2 corresponds substantially to the section according to FIG. 1 b) but here no display 7 is present, but simply upwards a disc 36 is arranged, which prevents fouling of the interior 21 of the housing upper part 8 , Optionally, it is possible to replace the disk 36 with an enlarging lens in order to make security features on the object 4 more clearly recognizable. In addition, specific diaphragms 35 are provided here, which prevent light from falling directly from the light sources 1 onto the observation disc 36. In the aperture 35 may be parallel to the axis of the light sources 1 extending planar sheets, but it is also possible, for. B. in a round disc 36, the diaphragm form in the form of a conical truncated cone. Again, on the object 4 and the polarizing filter 2 facing the end of the aperture 35, a filter 5 is provided which filters out light components from the spectral range of the light sources 1 (UV filter). It is also possible, if a sufficiently efficient UV filter 5 is used to completely dispense with aperture 35, and to put the filter 5 immediately in front of the disc 36, or replace the disc 36 directly by a filter 5.

For analyzing an object, the object with corresponding security features is now simply placed on a plane, and a device according to one of the FIGS. 1 and 2 is guided over the object such that the object is covered by the hole 27. It should be ensured that no light can get laterally between the object and the bottom of the housing in the interior 22, and thus can reduce the quality of the observation.

LIST OF REFERENCE NUMBERS

1

UV lamps

2

Polarizing filter, rotatable

3

cover glass

4

Object with security feature

5

filter

6

CCD color camera

7

TFT color LCD display

8th

Housing upper part

9

cover sheet

10

Lower part of housing

11

switch

12

vents

13

knobs

14

Connector for external display

15

Connection for external power supply

16

Connection for battery charger

17

bottom

18

top

19

handle notches

20

Handset with display

21

Cavity in the housing upper part

22

Dark room in the housing lower part

23

irradiated UV light, linearly polarized

24

irradiated UV light, not polarized

25

emitted visible light, optionally polarized

26

fixing screw

27

Hole in bottom of 10

28

Headboard of 1

29

Version of 1

30

Holder ring of 2

31

drive belts

32

engine

33

Drive wheel of 32

34

Leadership role for 2

35

dazzle

36

Disc / lens

Claims (18)

1. A device (20) for revealing security elements that are present in an object (4) and that have at least one photoluminescent segment which is characterized by linearly polarized photoluminescence and/or linearly polarized absorption, wherein at least one light source (1) emits light in the UV-range the at least one light source as well as at least one polarization filter (2) are arranged in such a way that the light (24) from the light source (1) is linearly polarized (23) by the polarization filter (2), strikes the object (4) and, respectively, the photoluminescent segments present therein, and photoluminescent light (25) from the segment can be observed through the same polarization filter (2) and wherein the photoluminescent light (25) from the segment lies in the visible range.
2. The device (20) as claimed in claim 1, characterized in that the light source is a UV light source (1) with an emission in the range from 180 to 500 nanometers, preferably in the range from 200 to 400 nanometers.
3. The device (20) as claimed in claim 1, characterized in that the light source is a broadband light source in front of which an appropriate bandpass filter is arranged, so that only UV light in particular in the range from 180 to 500 nanometers, preferably in the range from 200 to 400 nanometers strikes the object (4).
4. The device (20) as claimed in claim 3, characterized in that the bandpass filter is simultaneously also a polarization filter.
5. The device (20) as claimed in either of claims 2, 3 or 4, characterized in that the light source is a mercury vapor lamp, a laser light source or a halogen lamp or an arc discharge lamp.
6. The device (20) as claimed in one of the preceding claims, characterized in that the observation takes place through a filter (5) which substantially does not permit light in the wavelength range of the light source (1) to pass, while light in the wavelength range of the visible photoluminescent light (25) from the segment can pass substantially unimpeded.
7. The device (20) as claimed in one of the preceding claims, characterized in that the light (24) shone in and the photoluminescent light (25) from the segment pass through the same polarization filter (2) and the polarization filter (2) for observation can be rotated about an axis perpendicular to the plane of the polarization filter (2), in particular with the aid of a motor (32).
8. The device (20) as claimed in claim 7, characterized in that the polarization filter (2) can be rotated with the aid of a motor (32) with a rotation frequency in the range from 0.2 to 5 Hz, in particular preferably with a rotation frequency of 0.5 to 2 Hz.
9. The device (20) as claimed in either of claims 7 and 8, characterized in that the polarization filter (2) is enclosed in a mounting ring (30) and in that the polarization filter (2) is rotated by a drive belt (31) which runs around the mounting ring (30) and is driven by a drive wheel (33) moved by a motor (32), in particular the mounting ring (30) preferably being rotatably mounted via at least 3 tangentially engaging guide rollers (34).
10. The device (20) as claimed in one of the preceding claims, characterized in that a camera, in particular preferably a CCD color camera (6), is provided for the observation and that the image recorded by the camera is depicted on a display, in particular preferably a TFT-LCD color display (7), if appropriate following suitable image processing such as contrast adaptation, color adaptation, brightness adaptation, enlargement and/or resolution adaptation.
11. The device (20) as claimed in claim 10, characterized in that the camera is a multichip camera, in particular preferably a three-chip camera
12. The device (20) as claimed in one of the preceding claims, characterized in that the observation is carried out through a lens (36), in particular preferably through a magnifying glass.
13. The device (20) as claimed in one of claims 1, 2, or 5 - 12, characterized in that the light source (1) is a UV lamp, preferably a UV tube having a wavelength in the range from 200 to 390 nanometers, and in that the polarization filter (2) is a broadband linear polarizer which, particularly preferably, has a polarizing action in a wavelength range from 300 to 770 nanometers.
14. The device (20) as claimed in claim 13, characterized in that the light source (1) is a UV tube having a wavelength in the range from 350 to 370 nanometers.
15. The device (20) as claimed in one of the preceding claims, characterized in that means for checking further security features are additionally provided, it being possible for the further security features to be magnetic, electric, optical, electronic, electro-optical features.
16. The device as claimed in claim 15, characterized in that the further security features are selected from the group comprising bar codes, magnetic strips, conductivity, luminescence, photoluminescence, up-conversion (anti-Stokes), infrared signatures, electronically readable text (OCR text), including those with infrared text, X-ray fluorescence features.
17. A method for revealing security elements that are present in an object (4) and that have at least one photoluminescent segment which is characterized by linearly polarized photoluminescence and/or linearly polarized absorption, wherein light (24) in the UV-range from at least one light source (1) is linearly polarized (23) by at least one polarization filter (2), strikes the object (4) and, respectively, the photoluminescent segments present therein, and photoluminescent light (25) in the visible range from the segment is observed through the same polarization filter (2).
18. A method for revealing security elements according to claim 17, characterized in that a device as claimed in one of claims 1 to 16 is used.

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