JP5460819B2 - Security marking authentication device - Google Patents

Description

  The present invention belongs to the field of document or item authentication. The present invention relates to an apparatus for visual authentication of the presence of circularly polarized security markings on a document or item. The device is based on a special light source with a circular polarizing filter.

  In the field of valuable document certification or identity management, document authentication is often required. Authentication is confirmation or confirmation that something or someone belongs to a certain category, and at that time, a predetermined characteristic (security element, marking) indicating the affiliation is used.

  The present invention discloses an authentication device used to authenticate a document or item having a circularly polarized security marking, wherein the circularly polarized security marking uses an ink or coating composition comprising circularly polarized particles, Or it can be printed or coated by applying a laminate or film (foil) with circular polarization properties.

  Throughout this description, the term “authentication device” refers to a device used to authenticate a document or item with a circularly polarized security marking.

  According to the present invention, the circular polarization property is preferably implemented by a cholesteric liquid crystal polymer (CLCP). Such a polymer selectively reflects one circularly polarized component. This means that light having a predetermined circular polarization state (counterclockwise or clockwise, depending on the polymer) is mainly reflected within a predetermined wavelength range.

  Cholesteric liquid crystal materials are characterized by an internal helical supramolecular structure, whereby the refractive index is periodically modulated, the periodicity of which corresponds to the wavelength of visible light. As a result, such materials act as optical diffraction gratings, reflect light of specific wavelengths, and appear to be colored to the naked eye. Depending on the direction of the helical structure (right or left), light in one circular polarization state is mainly reflected (JL Fergason, "Cholesteric Structure-I Optical Properties," Molecular Crystals, Vol. 1, pp. 293- 307, 1966). Cholesteric liquid crystal materials are proposed as coloring means in US Pat. No. 3,766,061.

  To achieve time-stable and temperature-independent color properties, the cholesteric helical structure can be “frozen” by chemical crosslinking, that is, by polymerizing the liquid crystal material in the desired state, thereby producing a cholesteric liquid crystal. It is advantageous to obtain a polymer (CLCP). A photopolymerized cholesteric liquid crystal material is disclosed in GB 2166755 (A). Also, pigments made of cholesteric liquid crystal polymers are disclosed in EP 0 601 483 (A1), and such pigments can be used in coating compositions and as security markings. WO 94/22976 (A1) and WO 95/08786 (A1) are particularly directed to such coatings and security markings. Further documents relating to this context are German Patent No. 4418490 (A1), European Patent No. 0685749 (A1), WO 97/30136 (A1), US Pat. No. 6,597, No. 426, European Patent No. 087398 (A1), US Pat. No. 6,570,648, International Publication No. 00/47694 (A1), German Patent Application Publication No. 19922158 (A1). No. 6,641,874, WO 2005/105473 (A1), and WO 2006/063926 (A1).

  An authentication device for the mechanical detection of security markings containing cholesteric liquid crystal material is disclosed in DE 10211310 (A1). According to this document, the marking is illuminated with one or several light sources that are spectrally limited, for example “color” light-emitting diodes, and whether there is circular polarization in the light reflected by the marking. Is detected by the detection unit. However, this device cannot be used for visual authentication of cholesteric liquid crystal markings.

  According to the prior art, the visual authentication of circularly polarized security markings on documents or items is performed under “ambient light” using left and right circularly polarized filters, each with a left circularly polarized light respectively. The appearances of the markings seen through the filter and the right circular polarizing filter are compared. In this way, satisfactory results are obtained only if the illumination light has a good spectral quality. In many environments, ambient light levels are even lower (eg, less than 50 lux for night outdoor events or night identity management), which is useless for authentication tasks.

  The present invention discloses an authentication device for easy visual authentication of documents or items with circularly polarized security markings.

  In an important aspect of the present invention, the authentication device comprises a special light source capable of emitting left and right circularly polarized light. This light source is characterized by generating two light beams having opposite circular polarization (ie, a left circularly polarized light beam and a right circularly polarized light beam) separated in either space or time. To do.

  Thus, an authentication device for visual authentication of a document or item with a circularly polarized security marking comprises at least one light source and at least one circularly polarizing filter, the device for illuminating the marking on the document Left circularly polarized light and right circularly polarized light, and the circularly polarizing filter is preferably a left circularly fixed polarizing filter and a right circularly fixed polarizing filter, a mechanical variable circularly polarizing filter, and an electro-optic variable circularly polarized light. Selected from the group consisting of filters.

  In a first embodiment, two adjacent continuous rays of opposite circular polarization and having approximately the same intensity, preferably adjacent, simultaneously illuminate a region of a document or item with a circular polarization marking. In a preferred variant of this embodiment, the areas of the document are adjacent so that it is easy to compare the appearance of the markings under both types of polarization.

  In the relationship described herein, the illumination area of a document refers to an area that is actually illuminated by light rays, and does not refer to a special area that exists in advance on the document.

  In a second embodiment, a single beam of alternating circularly polarized light having an approximately constant intensity is directed to a region of a document or item that comprises a circularly polarized marking.

  In either case, the appearance of the circularly polarized marking changes according to the palm of the incident light. Accordingly, the beam of the authentication device is applied to the marking, the palm of the polarization of the beam is changed to each, and the appearance / appearance change of the marking is visually observed under each type of polarization. Under the same conditions, the document or item can be authenticated by comparing it with a guaranteed authentic marking appearance / change in appearance.

  A more quantitative evaluation of the polarization reflected by the marking can be made using a suitable photoelectric detector (eg photodiode), optionally with the aid of further optical elements (lenses, filters, etc.) and measured detection. This may be done using a corresponding automatic processing by the processing device.

(Detailed explanation)
The authentication apparatus according to the present invention includes a special light source that emits circularly polarized light. The device comprises at least one circularly polarizing filter, specifically a modified light pen, a modified flashlight, or a specially designed authenticity verification device to accommodate portable applications. Good.

  An important aspect of the present invention is the use of a light emitting diode (LED) as a light source. Several suppliers (Phillips, Nichia, etc.) are currently proposing white and “color” LEDs as high-efficiency light sources for portable applications. White LEDs emit light over the entire visible spectral region (i.e., 400 nm to 700 nm). “Color” LEDs emit light in a specific narrow wavelength range on the order of 50 nm in the ultraviolet, visible, or infrared spectral region.

  The efficiency of the LED can be as high as 150 lumens per watt of power, i.e. more than 10 times the efficiency of an incandescent lamp. For this reason, independence is extended 10 times compared with a light bulb, which is an essential advantage in portable applications where independence is required. Typical operating conditions for white LEDs in flashlights range from 20V (for light output from 25 cd to 30 cd) from 3.2V to 3.6V to 1A (for light output above 100 lumens). It is.

  Thus, the selection of LEDs in the present invention can provide significant advantages over the prior art. Because i) the lighting conditions of the light source, and hence the marking, are precisely defined and remain the same for all certifications performed by the device, ii) with a standard set of commercially available AAA batteries This is because the independence of the authentication device in continuous use can be as long as one week compared to less than one day in the case of an incandescent lamp.

  Referring to FIG. 1, in the first embodiment of the authentication device, a split type right / left circular polarizing filter composed of two semicircular filter plates (in front of a single white light source L1) ( Use FL, FR) to obtain two adjacent rays with opposite circular polarization and illuminate adjacent areas (M1, M2) of the marking (M) simultaneously. Optionally, a positive lens or a Fresnel lens (LE) may be part of the authentication device. The lens is placed at a distance d1, d2 from the filter and the marking, respectively, between the polarizing filter and the marking so as to form an image of the filter in the plane of the marking. In this way two orderly separated regions with oppositely polarized illumination on the marking are obtained. The filter is disposed completely inside the authentication device, and the authentication device comprises L1, FL / FR, and LE in the same container.

  Referring to FIG. 2a, in a second embodiment of the authentication device, the two white light sources (L1, L2), each having a left polarizing filter (FL) and a right polarizing filter (FR), are switched on and off alternately. Or illuminate the marking (M) with alternating left and right circularly polarized light.

  As is well known to those skilled in the art, alternating circular polarization can be achieved in other ways, one of which is to mechanically switch either the palm filter or the filter palm. This latter can be achieved, for example, by a rotating polarizing filter component, ie a rotating λ / 4 plate in front of a stationary linear polarizing filter, or by a rotating linear polarizing filter behind a stationary λ / 4 plate. Mechanical polarization switching allows a single light source to be used, providing equivalent and clear characteristics for both left and right circularly polarized illumination. This is especially true in the case of rotating filter parts.

  Referring to FIG. 2b, in a modification of the second embodiment, instead of a pair of left and right circular polarizing filters, a single electric as described in DE 10211310 is used. An optical circular polarizer (EOCP) is used with a single white light source (L1) to generate alternating left and right circular illumination of the marking (M). The electro-optic circular polarizer (EOCP) is connected to an electric drive unit (DR) that controls the polarization state (left circle or right circle) of the EOCP.

  Referring to FIG. 2c, yet another modification of the second embodiment, applicable to both variants outlined above, uses a photocell (photocell), in particular a color sensor (CS), to mark ( Measure the intensity of the light reflected by M). The signal of the color sensor is processed by the microprocessor (μP). The microprocessor (μP) switches on and off the light sources (L1, L2) and drives the electro-optic circular polarizer (EOCP) respectively. Also, the intensity and color of the reflected light are evaluated according to the selected illumination condition and a predetermined reference value stored therein, and the authentication result is output to the display (D). This result can indicate either a simple presence or absence of a circularly polarizing material, or can provide additional information about the color of the polarizing material.

  Referring to FIG. 3a, in a further embodiment, a plurality of first white light sources (L1) having a left circular polarization filter (FL) are arranged on the optical axis of the authentication device and have a right circular polarization filter (FR). (Ie, at least two) second white light sources (L2a, L2b,...) Are arranged around the first light source (L1). The polarizing filters may be implemented as concentric plates (FL, FR) and the order of the polarizing filters may be reversed. An optional lens may be present in the light path, but preferably each of the light sources (L1, L2a, L2b,...) Has its own lens for making its light output into the shape of a light beam.

  In operation, the first light source and the plurality of second light sources are alternatively switched on and off, preferably with alternating left and right circularly polarized light of the same light intensity. The marking is illuminated. As outlined above and with reference to FIG. 3b, this embodiment further includes a photovoltaic cell (photocell) for automated measurement and evaluation of the intensity and color of the light reflected by the marking. In particular, a color sensor (CS), a microprocessor (μP) and a display (D) can be combined.

  The light sources used in the embodiments outlined above may further be a “color” LED that emits light in a specific narrow wavelength range, for example in the ultraviolet, visible, or infrared spectral region, as large as 50 nm, It can be chosen as a spectrally selectable light source, such as a laser diode (LD) with a wavelength.

  Referring to FIG. 3a, in the fourth embodiment, a first white light source (L1) having a first polarizing filter (FL) and a spectrally selectable having a second polarizing filter (FR). A plurality of separate (color) second light sources (L2a, L2b,...) Are used in conjunction with each other. In a modification of this embodiment, the first light source can be a spectrally selectable light source.

  Referring to FIG. 4a, in yet another embodiment, a plurality of spectrally selectable (color) separate first light sources (L1a, L1b,...) Having a first polarizing filter (FR). ) And a plurality of spectrally selectable (color) separate second light sources (L2a, L2b,...) Having a second polarizing filter (FL).

  During operation, the light source is switched on and off alternatively, and the result of visually illuminating the marking (M) with light of left and right circular polarizations of different colors is visually determined. Can be done. An optional lens (LE) may be present to focus the light on the marking (M). An additional non-polarized white light source (L3) may also be provided to illuminate the marking under normal reading conditions.

  According to FIG. 4b, in an alternative variant of this embodiment, a simple photovoltaic cell (photocell) (P) is used to measure the intensity of the light reflected by the marking for different colors and polarizations. The photocell signal is processed by the microprocessor (μP), which switches on and off the light sources (L1a, L1b,..., L2a, L2b,..., L3), The intensity of the reflected light is evaluated according to the selected illumination condition and a predetermined reference value stored therein, and the authentication result is output to the display (D).

  Throughout the present invention, circular polarizing filters can also be combined with color filters to select a predetermined spectral region.

  The illumination intensity at the working distance on the marking (M) is preferably 50 lux or more, more preferably 500 lux or more. It is noteworthy that the working distance is defined as the distance that the authenticator should be placed from the document or item in order to inspect the marking under optimal conditions. In embodiments using simultaneous illumination or adjacent rays, the working distance is the distance at which the image of the polarizing filter is obtained in the plane of the marking. The working distance is chosen between 1 cm and 20 cm, more preferably between 2 cm and 10 cm, depending on the embodiment.

  The authentication device is designed as an automatic pass / fail confirmation machine including a photocell (P) having an optional filter, a processor (μP), a control switch, and a display device (D) in addition to a polarized light source. It is worth noting that the authentication result may be output. The operation of automatically turning on and off the LED, reading the signal from the photocell (P), processing and storing the read signal value, deriving the authentication result, and displaying the authentication result automatically The function to be performed is provided by firmware embedded in the microprocessor (μP).

  The preferred embodiment of the authentication device is a small, lightweight, easy to use and robust device.

  In a preferred embodiment, the authentication device has the shape of an elongated cylinder or bar, preferably having a length on the order of 10 cm. The cylinder or rod preferably has a cross-section on the order of 1 square centimeter to 5 square centimeters, in which a light source, a filter and optional further optical elements are arranged and necessary with a battery serving as a power source. For example, control electronic circuits and logic circuits are arranged. The necessary switches and indicators that serve as a user interface are ergonomically placed on the rear and / or outer surface of the cylinder or bar, and the light output passes through the front end of the cylinder or bar.

  In a further preferred embodiment, the authentication device is made from a group of materials consisting of plastic material, stainless steel, aluminum and aluminum alloy, preferably the entire device weighs no more than 100 g.

  In yet another preferred embodiment, the authentication device has a box shape, preferably on the order of 50 mm × 40 mm × 30 mm, and is placed on the marking of the document to be authenticated. The box has two windows so that a human user can see the markings under left and right circular polarization illumination, respectively. Inside the box are a light source, a filter, and optional additional optical elements, along with a battery that serves as a power source, and if necessary, control electronics and logic circuits. The necessary switches and indicators that serve as the user interface are ergonomically placed on the outer surface of the box, and the light output that illuminates the document passes through the marking-facing window corresponding to the viewing window.

  The invention will now be further described with reference to the drawings and exemplary embodiments.

FIG. 1 is a diagram schematically illustrating an authentication apparatus according to the present invention. The authentication apparatus includes a single white light source (L1), two semicircular left circular polarization filters, and a right circular polarization filter (FL, FR). ) And an optional lens (LE), and two adjacent regions (M1) with simultaneous and opposite circularly polarized continuous illumination on the marking (M) for assisted visual authentication of the marking (M) , M2). FIG. 2 is a schematic drawing of an authentication device according to the invention, the authentication device for alternating illumination of markings (M) with reverse circular polarization, a) marking (M) The first and second white light sources (L1, L2) are used together with the first and second left polarizing filters and right polarizing filters (FL, FR) for the supported visual authentication. FIG. 2 schematically depicts an authentication device according to the invention, the authentication device for alternating illumination of markings (M) with reverse circular polarization, b) marking (M) A single white light source (L1) is used with an electro-optic circular polarizer (EOCP) and a drive unit (DR) for assisted visual authentication. FIG. 2 is a schematic drawing of an authentication device according to the present invention, the authentication device for alternating illumination of markings (M) with reverse circular polarization, c) marking (M) One of the embodiments a) or b) is used with an additional color sensor (CS), a microprocessor (μP), and a display (D). FIG. 3 schematically depicts an alternative authentication device according to the invention, which is for alternating illumination of markings (M) with reverse circularly polarized white light, a) A single first white light source (L1) having a first circular polarization filter (FL) and a first light source (L1) is arranged around the first light source (L1) for assisted visual authentication of the marking (M) And a plurality of second white light sources (L2a, L2b,...) Having a second circular polarization filter (FR). FIG. 3 is a schematic drawing of an alternative authentication device according to the invention, the authentication device for alternating illumination of markings (M) with reverse circularly polarized white light, b) An additional color sensor (CS), a microprocessor (μP), and a display (D) are used for automatic authentication of the marking (M). FIG. 4 schematically depicts an alternative authentication device according to the invention, which is for alternating illumination of markings (M) with reverse circularly polarized colored light, a) A plurality of spectrally selectable (color) separate first light sources (L1a, L1b,...) With a first polarizing filter (FR) for assisted visual authentication of the marking (M). A plurality of spectrally selectable (color) separate second light sources (L2a, L2b,...) Having a second polarizing filter (FL), and optionally a non-polarized white third A light source (L3) and optionally a lens (LE) are used. FIG. 4 schematically depicts an alternative authentication device according to the invention, the authentication device for alternating illumination of markings (M) with reverse circularly polarized colored light, b) An additional photocell (P), a microprocessor (μP), and a display (D) are used for automatic authentication of the marking (M). FIG. 5 shows an exploded view of a first embodiment of an authentication device according to the invention, which is a modified flashlight, in a cylindrical aluminum housing, with a lens (103), Semicircular left and right polarizing filters (102L, 102R), a white light source (101), an on / off switch (S), and a battery (100), and a reverse circle on the document under inspection It generates two adjacent continuous rays of polarized light. FIG. 6 shows an exploded view of a second embodiment of an authentication device according to the present invention, which is a modified flashlight, in which a first polarizing filter ( 202a) having a first white light source (201a), the first white light source (201a) being surrounded by four second white light sources (201b) having a second polarizing filter (202b) The device generates alternating, circularly polarized illumination on the document under examination. FIG. 7 is a diagram showing a third embodiment of an authentication device according to the present invention, which is designed as a confirmation box for viewing the marking (M) under left and right circularly polarized light. A) is a diagram showing a schematic cross section of the unit of the confirmation box, the unit comprising a white light source (101), a circularly polarizing filter (102), And a Fresnel lens (103). FIG. 7 is a diagram showing a third embodiment of an authentication device according to the present invention, which is designed as a confirmation box for viewing the marking (M) under left and right circularly polarized light. B) is an exploded view of the confirmation box, and illustrates the positions of the switch (S) and the battery (100). FIG. 7 is a diagram showing a third embodiment of an authentication device according to the present invention, which is designed as a confirmation box for viewing the marking (M) under left and right circularly polarized light. C) is a diagram showing the shape of a confirmation box, and is a diagram for explaining a feasible design.

  Referring to FIG. 5, in a first embodiment used for assisted visual authentication, light is provided by an LED (101) (white LED, B5B-430-JB, Roithner, Vienna) and a lens (103 ) (304.OM.3 plastic lens, diameter 16.5 mm, focal length +30 mm). Between the LED and the lens, two semicircular circular polarization filters (102L, 102R) having opposite palm properties (left and right, respectively) are arranged. The distance between the filter and the lens is chosen such that an image of the filter is formed at a distance of 5 cm on the opposite side of the lens, where an item or document holding the marking is placed for inspection. This makes the separation lines between simultaneously illuminated areas with opposite polarization visible, and these areas are thus properly defined. Also, a mask can be additionally placed on the filter to project a logo or text instead of just a simple ray. The entire apparatus was implemented with an aluminum cylinder 80 mm long and 14 mm in diameter. In addition to being convenient and compact, this device offers the advantage that the filter is hidden inside the device and otherwise looks like a regular light pen, so that an external observer can Not necessarily aware of what kind of properties are being investigated.

  The use of LED light sources provides significant independence to the device. The battery is a simple AAA battery as commercially available.

  Referring to FIG. 6, in a second embodiment, also used for assisted visual authentication, light is provided by five LEDs (201) (Roithner, Vienna) and the first one (white LED, B5B- 430-JB) is placed on the optical axis, the other four (blue LEDB5B-437-IX 470nm, green LEDB5B-433-20 572nm, red LEDB5B-435-TL 625nm, infrared LEDLED850-04VP 850nm ) Are arranged in a tight ring around the first LED. The first LED is provided with a clockwise circular polarizing filter (202), and the other four LEDs are provided with a counterclockwise circular polarizing filter (203) (that is, opposite to the first one). It is done. These inner and outer diodes are switched on and off alternatively at regular time intervals so that the item under inspection is illuminated alternately with left and right polarized light . The number and arrangement of diodes in the device is not important as long as these two sets illuminate the region of interest with similar intensity. The entire apparatus was implemented with an aluminum cylinder 100 mm long and 18 mm in diameter.

  Referring to FIG. 7a, in a third embodiment having the form of a confirmation box, also used for assisted visual authentication of a document or item, two different regions of the document or item under examination have opposite polarizations. Illuminated by separate LEDs through a circular polarizing filter with one area through the right polarizing filter and the other through the left polarizing filter. Each region is visually inspected through the same polarizing filter used to polarize the illumination, and a magnifying lens (Fresnel lens) is provided to increase the visibility of document or item details. This embodiment is particularly useful when the markings on the document or item show only a slight polarization effect, or when the marking or its details are of very small dimensions. The confirmation box was implemented in a plastic case with dimensions of approximately 50 mm × 35 mm × 25 mm. FIG. 7b shows an exploded view of the entire confirmation box and FIG. 7c shows a view of the box from the outside.

  The authentication device of the present invention can be used to authenticate currency, securities, vouchers, identity verification documents, access documents, event tickets, transportation tickets, opening tapes, product labels, or packaging materials.

The method of visual authentication of documents or items with circular polarization security markings is:
a) illuminating a marking on a document with a device according to the invention that emits left and right circularly polarized light;
b) visually determining the light reflected by the marking, thereby authenticating the document or item.

  In a variant of the method, preferably an adjacent area of a document or item with a circular polarization marking is illuminated simultaneously by two rays with opposite circular polarization.

  In another variation of the method, a document or item with a circular polarization marking is illuminated by a single light beam with alternating circular polarization.

  In yet another variation of the method, the light source is selected from the group consisting of a white light emitting diode (white LED) and a “color” light emitting diode (color LED).

In a method of automatic authentication of a document or item with circularly polarized security markings using a device according to the invention that emits left and right circularly polarized light, the device is a photovoltaic cell selected from the group consisting of a photocell and a color sensor And a microprocessor (μP) and a display (D), the method comprising:
a) an automatic step of switching on and off the light source by a microprocessor (μP);
b) an automatic step of reading the signal from the photocell (P) or color sensor (CS) to the microprocessor (μP);
c) an automatic step of processing and storing the read signal value in a microprocessor (μP);
d) an automatic step of deriving an authentication result based on a preset criterion stored in the microprocessor (μP);
e) An automatic step of outputting the authentication result to the display (D).

  The examples and figures presented in this description are for illustrative purposes only and are not to be construed as limiting the scope of the invention in any way.

Claims (7)

An authentication device for visual authentication of a document or item with a circularly polarized security marking (M) comprising:
Comprising at least two light sources ( L1, L2 );
The authentication apparatus includes a left polarization unit (FL) and a right polarization unit (FR) that generate reverse circularly polarized light that alternately alternates, and a switch unit that alternately switches on / off the light sources (L1, L2). , in order to form the circularly polarized light security markings (M) illumination area in the left circularly polarized light and right circularly polarized light alternating on, to be able to generate single light beams having opposite circular polarization alternating,
The authentication device comprises an elongated cylindrical or bar shape having a cross section of 1 square centimeter to 5 square centimeters,
Thereby, a user can visually observe the appearance or change of the security marking under each type of circularly polarized light. The authentication apparatus according to claim 1 , wherein the light of the light source is concentrated on the document or item using a positive lens (LE) or a Fresnel lens (LE). The authentication apparatus according to claim 1 or 2 , wherein an illumination intensity at a working distance on the marking (M) is 50 lux or more. 4. The authentication device according to claim 3 , wherein an illumination intensity at a working distance on the marking (M) is 500 lux or more. The authentication device according to any one of claims 1 to 4 , wherein the authentication device is made of a material of a group consisting of a plastic material, stainless steel, aluminum, and an aluminum alloy. 6. Any one of claims 1 to 5 for the authentication of currency, securities, vouchers, identity documents, access documents, event tickets, transportation tickets, opening tapes, product labels or packaging materials. Usage of the described authentication device. A method of visual authentication of a document or item with a circularly polarized security marking (M), comprising:
Illumination area with left and right circularly polarized light alternating on the circularly polarized security marking (M) using the apparatus of any one of claims 1 to 5 that emits left and right circularly polarized light Illuminating the marking on the document or item by emitting left and right circularly polarized light by emitting a single light beam with alternating circularly polarized light that alternates to form
Visually determining the appearance or change of the security marking illuminated under each type of circularly polarized light from the light reflected by the marking, and authenticating the document or item;
A method characterized by comprising: