WO2001037226A1

WO2001037226A1 - Apparatus and method for verifying the authenticity of documents, for example bank notes or cheques

Info

Publication number: WO2001037226A1
Application number: PCT/FR2000/003189
Authority: WO
Inventors: Bertrand Gaymard; Frédéric GAYMARD; Pierre Pascal; Jean-Louis Vincent
Original assignee: Societe De Montage Et Cablage Electronique
Priority date: 1999-11-17
Filing date: 2000-11-16
Publication date: 2001-05-25
Also published as: AU1867501A; FR2801125B1; FR2801125A1; EP1232485A1

Abstract

The invention concerns a method for verifying the authenticity of documents, for example bank notes or cheques, characterised in that it consists in successively exposing the document (D) to be controlled, to several light sources (1A, 1B, 1C, 1D,...) consisting of optoelectronic components and emitting, each, a different light spectrum (S1, S2, S3,...); sensing the light rays (LR1, LR2,...) emitted by the optoelectronic components and reflected by the document (D) and/or transmitted through the latter, by means of receiver cells formed by photosensitive components (2A, 2B,...) enabling to convert the lights received on their sensing surface into analog electric signals transmitted to a unit digital signal processing and analysis (UTANS), after being shaped and converted into digital signals, said processing unit incorporating an algorithm and being configured and programmed to analyse the digital signals received and for transmitting a result concerning the authenticity of the controlled document.

Description

Apparatus and method for verifying the authenticity of documents, for example bank notes or checks.

The present invention relates to an autonomous and portable device for verifying the authenticity of banknotes, checks or other documents. It also relates to the detection method implemented in the construction of this device and for its use.

Many devices and methods are known for the purpose of detecting counterfeit banknotes.

The invention relates more particularly to apparatus and methods using optoelectronic components both at the level of light emission and at the level of reception of the rays reflected by the verified document.

Devices and methods of this kind are, for example, described in documents FR-2,759,187 and WO-97/46982.

Document FR-2,759,187 describes a device for detecting counterfeit banknotes, comprising a housing in which are housed optoelectronic components powered by a battery and capable of generating light intended to be reflected by the banknote to control, a photosensitive electronic component making it possible to capture the light reflected by this banknote and to transform it into an electrical quantity, a specific integrated circuit configured to measure this electrical quantity and compare it with a pre-determined "true / false" detection threshold -regulated and to transmit a result, and a signaling means making it possible to warn the user when the result of the analysis is negative and / or positive, the housing comprising a transparent face intended to be applied to the banknote at control; the optoelectronic components consist of blue light-emitting diodes or blue LEDs placed behind and near this transparent face, so as to obscure outside light and to make said device insensitive to any light other than that generated by said blue light-emitting diodes, when its side formed by said transparent face is plated on the bank note to be checked.

This device gives interesting results; however, it does not take into account the state of soiling or aging of the controlled banknotes, this . ,,, - _« _ 1/37226

which leads him to report as non-genuine, dirty and / or very used banknotes which are generally small denominations, while these banknotes are perfectly legal.

In document WO 97/46 982, a banknote checking apparatus is described comprising four LEDs, namely red, green, blue and infrared, used to illuminate a banknote, a light detector for detecting red lights, green, blue or infrared reflected by said bill, A / D means for converting the light detector output signal into a digital signal, means for selectively limiting the output gain of said A / D means in order to obtain a signal output indicative of one of said selected colors, and means for providing said output signal to means for determining the validity of the ticket.

The purpose of this device is to try to determine with precision the colors of banknotes, by carrying out measurements by reflection on one of the opposite faces of said banknotes, of the three primary colors emitted by LEDs green, red, blue, in order to detect possible variations in nuances differentiating a counterfeit note from a real one. However, modern printing means, such as color copiers recently appeared on the market, faithfully reproduce these nuances, so that counterfeit notes which would be manufactured with such materials would in fact be undetectable with the device according to the document WO 97/46 982. In addition, the process implemented in this device also does not take into account the level of soiling and / or aging of the paper, which leads to analysis results signaling "false" authentic banknotes .

An object of the invention is to remedy the aforementioned drawbacks and inadequacies of counterfeit banknote detectors operating by analyzing the light reflected by the controlled banknote, lit by one or more LEDs.

According to the invention, this objective is achieved by a process according to which the document to be checked is successively exposed to several light sources consisting of optoelectronic components and each emitting a different light spectrum, the light reflected by the document, and / or transmitted through it, by means of receiving cells constituted by photosensitive components making it possible to convert the lights received on their sensitive surface, into analog electrical signals transmitted to a processing unit, after shaping and conversion in digital signals, said processing unit integrating an algorithm and being programmed to analyze the digital signals received and to issue a result on the authenticity of the checked document

According to another characteristic arrangement of the invention, the signals from the exposure of the document to one or more light sources are analyzed to determine the level of soiling and / or aging of said document, and the information resulting from this analysis is taken taken into account by the processing algorithm for determining the authenticity of the checked document

The apparatus according to the invention comprises

- a measurement stage consisting of several optoelectronic components for emission of different light spectra and of several receiving cells, making it possible to execute at least two of the authentication tests below

• measurements of the degree of soiling and / or aging of the document,

• measurement of the level of intensity of violet color light reflected by the document exposed to blue light,

• measurement of the light intensity resulting from the fluorescence of the document exposed to violet light,

• measurement of the level of intensity of violet color light reflected by the document exposed to violet light,

• measurements of the level of intensity of infrared light reflected by the document exposed to infrared and or red light, - a stage for shaping the electrical signals coming from the measurement stage and allowing in particular:

• amplify the electrical signals;

• filter electrical signals;

• clip electrical signals;

- an Analog-Digital converter stage allowing Analog / Digital conversion of analog electrical signals coming from measurement signals, to;

- a Digital Signal Processing and Analysis Unit stage (UTANS), which may include:

• a microprocessor;

• and / or a microcontroller;

• and / or programmable logic;

• and / or a digital signal processing system (DSP)

- an output Human-Machine Interface stage making it possible to give the user data such as the authenticity of the document tested, as well as system parameters, by means of, among others:

• LEDs;

• and / or displays;

• and / or sound signals;

• and / or vibrators.

The main advantage of the method and the device for checking the authenticity of documents such as banknotes is very high reliability, resulting in particular from taking into account signals from several sources of different measurements, in particular signals making it possible to measure the level of soiling and / or aging of said documents.

The aims, characteristics and advantages above, and others still, will emerge more clearly from the description which follows and from the appended drawings in which:

Figure 1 is a partial view, schematic of the apparatus according to the invention.

FIG. 2 is a schematic view illustrating the measurement of the lights reflected by one of the faces of the controlled document, successively lit by several different light sources.

FIG. 3 is a schematic view showing the measurement of the lights reflected by the two faces of the controlled document and of the lights passing through the latter.

Figure 4 is a diagram of the light intensity (%) emitted by a 430 nm "super blue" LED.

Figure 5 is a diagram of the chromatic visibility of the human eye.

FIG. 6 is a diagram of the light intensity, perceived by the human eye, of a 430 nm "super blue" LED.

Figure 7 is a schematic view illustrating the mounting of an LED emitting through a light filter.

Figure 8 is a schematic view showing the mounting of a photosensitive receiver receiving light through a light filter.

FIG. 9 is a schematic view illustrating another assembly of a photosensitive receiver receiving light through a light filter.

Figure 10 is a diagram of the RGB components on a yellow gradient. Figure 1 1 is a diagram of the RGB components on a gray gradient.

Figure 12 is a diagram of the light emitted by a 430 nm "super blue" LED through a U-360 light filter.

FIG. 13 is a diagram of the light perceived by a photosensitive receiver through a U-360 light filter, in the case of a light source constituted by a 430 nm "super blue" LED.

Figure 14 is a diagram of the "ideal" transfer function of the light filter.

Figure 15 is a diagram of the possible "ideal" transfer function of the light filter.

FIG. 16 is a schematic view of an electrical assembly making it possible to regulate the level of light intensity emitted by the LEDs.

FIG. 17 represents an assembly making it possible to regulate the electric current supplying the LEDs.

Figure 18 shows the structural flowchart of the device.

Figures 19A and 19B show a possible algorithm for taking measurements from the device.

Reference is made to said drawings to describe interesting examples, although in no way limitative, of implementation of the method and production of the apparatus according to the invention.

For a good understanding of the following description and of the claims, it is specified that:

- "LED" means "Light-emitting diode"

- "UTANS" means digital signal processing and analysis unit; - "DSP" means "Digital signal processing"

As indicated previously, the method and the apparatus according to the invention are intended to make it possible to verify the authenticity of various documents and, more particularly advantageously, the authenticity of banknotes.

According to the method of the invention, document D is successively exposed to several light sources consisting of optoelectronic components 1A, 1B, ... and each emitting a different light spectrum S1, S2, ... the light reflected LR1, LR2, by said document or transmitted through it, by means of receiving cells constituted by photosensitive components 2A, 2B, making it possible to convert the lights received on their sensitive surface 2a, 2b, into analog electrical signals transmitted to a UTANS processing unit, after shaping and conversion into digital signals, said processing unit integrating an algorithm and being configured and programmed to analyze the digital signals received and to issue a result on the authenticity of the ticket checked.

The measurement system applying this optical measurement method can be placed, either on one side of the document (FIG. 2) in which case it performs measurements only on this same side, or placed on either side of the document in order to analyze both sides of it (Figure 3). In the latter case, it is possible, in addition to the analyzes of the various reflected light rays, to carry out analyzes of the light rays transmitted through the document.

The method and the device according to the invention are based on the use of optoelectronic components both at the level of the emission of light and at the level of the reception thereof.

The light emission on the document is characterized:

^• at the level of analysis of the rays reflected by the document (on one or both sides):

- by sending separate light spectra and this successively.

These different light spectra are: 1. included approximately in the band of wavelengths from 380 nm to 400 nm (or even 410 nm) (violet light);

2. identical to the spectra of light emitted by a light-emitting diode (LED) having a wavelength emission peak between 400 and 450 nm;

3. included in the band of wavelengths covering the color blue or green or red or in the infrared.

• at the level of the analyzes of the rays transmitted through the document:

- by sending separate light spectra and this successively.

These different light spectra are:

1. included approximately in the band of wavelengths from 380 nm to 400 nm (or even 410 nm) (violet light);

3. included in the band of wavelengths covering the colors blue or green or red;

4. included in the infrared wavelength band.

The emissions of these light spectra are produced by one or more emitting cells composed of light emitting diodes (LEDs) and light filters.

These various light-emitting diodes (LEDs) are:

- LEDs whose emission peak has a wavelength between 400 nm and 450 nm, usually called "super blue" color (example: "super blue" LED 430 nm, Figure 4). The human eye (Figure 5) perceives well, when the lighting of the "super blue" LEDs, a light blue (cyan) (figure 6), but their emission peaks are in a color located between purple (420 nm) and indigo (440 nm) (figure 4), which differentiates them from the so-called blue LEDs whose emission peak is generally around 470 nm, wavelength corresponding well to the blue additive primary color;

- Green and / or red LEDs;

- LED emitting infrared rays.

These LEDs are mounted in different ways:

For "super blue" LEDs (analyzes by reflections and transmissions through the document)

A) unfiltered "super blue" LEDs

The LED (s) 1A emit their light spectrum S1 directly on document D;

B) filtered "super blue" LEDs

The LED (s) (1 B) emit through a light filter 3 limiting the spectrum of light emitted S2 on document D to wavelengths between 380 nm and 400 nm (or even 410 nm) (purple light ). The mounting of this light filter is shown in Figure 7 in which the reference 4 represents an opaque hollow body, while the reference 5 represents the connection wires, while the light emitted is shown in Figure 12. This filter light is therefore opaque at wavelengths greater than 400 nm (or even 410 nm) (Figure 14), possibly this light filter can be transparent at wavelengths greater than 650 nm (see Figure 15). For the green and / or red LEDs (analyzes by reflections and transmissions through the document)

The LED (s) 1C, 1 D directly emit their light spectra S3, S4 on document D.

For infrared LEDs (analysis by reflections and transmissions)

The LED (s) 1 E emit their light spectra directly on document D.

After one of the lights emitted by the emitting cell 1A, 1 B, 1 C, 1 D, 1 E has been reflected by the document D, it is picked up by a receiving cell.

This cell (light receiver) is made up of photosensitive components (such as, for example: photodiode, phototransistor, photoresistor, etc.) which make it possible to convert the light received on their sensitive surfaces into an analog electrical signal.

These photosensitive components are mounted in two ways:

A) Unfiltered light receiver

The receiver 2A directly receives the spectrum of reflected light LR1 from document D.

B) Filtered light receiver

The receiver 2B receives the light reflected LR2 by document D through a light filter 6 limiting the spectrum of light received at wavelengths less than 400 nm (or even 410 nm) (FIG. 13).

This light filter is therefore opaque at wavelengths greater than 400 nm (or even 410 nm) (Figure 14), possibly this light filter can be transparent at wavelengths greater than 650 nm (see Figure 15). These photosensitive components equipped with the light filter can be found directly on the market.

You can use a broad-spectrum photosensitive component (usually visible light, plus some infrared) and place the light filter in front of it, in order to eliminate the wavelengths, received by the receiver, greater than 400 nm (or even 410 nm) or located between 400 nm (or even 410 nm) and 650 nm. Mounting examples are shown in Figures 8 and 9; in these figures, the reference 7 designates an opaque hollow body while the reference 8 represents the connection wires.

In order to maintain the most constant light intensity emitted at the document level, the LEDs of the emitting cell are powered by a regulation cell 9. This cell makes it possible to regulate the level of light intensity emitted by the LEDs in order to obtain reliable measurements and therefore a correct opinion on the authenticity of the document. This regulation can be done:

1. either by applying a stabilized voltage U to the LED assembly, by means of a circuit including a current limiting resistor R (FIG. 16), circuit commonly used to limit the current in an LED. This method is the simplest and most economical, but has the major disadvantage that the current flowing in the LED is directly related to the temperature. In fact, when the LED is powered, a temperature rise T occurs at the level of the internal semiconductor which modifies the direct voltage Vf of the LED and thus modifies the current I flowing in the latter according to the law:

l (T) = (U-Vf (T)) / R

We can see that I depends directly on the temperature T.

In addition, depending on the geographical area of use or according to the periods of the year, the measurement system is not subjected to the same temperature T, it follows that, here too, the light power emitted by the LED varies , distorting the measurements. 2. either by directly regulating the current supplying the LEDs by means of a constant current generator (figure 17). This method, although a little more complicated and less economical to carry out than the first, has the enormous advantage that the current regardless of the temperature situated approximately between 0 and 50 ° C is only very little dependent on the temperature both the semiconductor and the temperature of the ambient medium.

A large number of diagrams of constant current generators which are easy to implement at low cost can easily be found in technical brochures or books. They generally and mainly use transistors or operational amplifiers.

By means of the method and of the optical measurement system according to the invention, six types of measurements by reflections and four types of measurements by transmissions can be carried out through the document of these various lights or rays on the document.

The measurements made by light reflections are:

• Measurement (s) of the level of soiling or aging (without distinguishing between the two) of the document (originally white paper)

This measurement is made by lighting a "super blue" LED 1A. The light emitted by the "super blue" LED 1A is projected onto the document D. Part of the light is reflected LR1 by the document D towards the photosensitive element 2A.

The electrical signal produced by the photosensitive element 2A is directly proportional to the soiling or aging of the document.

In fact, when a paper gets dirty, it is said to blacken, just as when a paper ages, it is said to turn yellow. Indeed, in each case, the tint of the paper, originally white, changes either by soiling towards a gradient of black (greyness), or by aging towards a gradient of yellow. We know that any color is the composition of the three additive primary colors which are red, green and blue. Each secondary color can be described by a mixture of these three primary colors and noted by an RGB index (red, green, blue). For example, white corresponds to an index (255-255-255) and black to an index (0-0-0), similarly pure yellow corresponds to an index (255-255-0) and gray to an index (120-120-120).

We can see in Figures 10 and 11, the level of the RGB indices as a function, respectively, of the yellow gradient or the gray gradient. In each case, the blue component varies, while on the gradient of yellow between the white part (255-255-255) and pure yellow (255-255-0), red and green do not vary. It follows that to check the state of soiling or aging (or the component of both) of a paper (originally white), only the study of the level of the blue component is interesting.

This measure allows:

- determine the level of soiling or aging of the paper;

- adapt the algorithm of the digital signal processing and analysis unit according to this measurement.

• Measurement of the level of soiling and aging (distinguishing between the two) of the document (originally white paper).

This measurement is made by successively lighting a "super blue" LED 1A and a red LED 1 D (and / or green 1C). The light S1, S3, S4 emitted respectively by the LEDs 1A, 1 C and 1 D comes to be projected on the document D. A part of the light is reflected LR1 by the document D towards the photosensitive element 2A.

Indeed, to determine both the aging and the soiling of the paper, we can add to the study of the reflected blue component, the study of one or two other reflected additive primary colors (green and / or the Red). So, for example, taking the study of the blue reflected component and red, you can get an RGB index of 200-xxx-200 for dirty paper, while you can have an RGB index of 255-xxx-200 for aged paper. In this way, the presence of a significant difference between the level of red (or green) and blue indicates that the paper has aged, the greater this difference and the more the paper is "old". The absence of a significant difference between the level of red

(or green) and blue makes it possible to determine that the paper has apparently not aged and thus only the study of the level of blue is sufficient to determine the state of soiling of the paper. The lower the blue level index, the dirtier the paper. In order to obtain even more precise results on the degrees of aging and soiling of the document, it is interesting to carry out an analysis of the paper by taking the study of the three reflected components blue, green and red.

These measures allow:

- to determine the level of soiling and also of aging of the paper;

- adapt the algorithm of the digital signal processing and analysis unit according to these measurements.

Measurement of the level of intensity of violet light reflected by the document exposed to blue light

This measurement is made by lighting a "super blue" LED 1A. The light S1 emitted by the "super blue" LED 1A is projected onto the document D. Part of the light is reflected LR2 by the document D and passes through a light filter 6 towards the photosensitive element 2B.

The electrical signal produced by the photosensitive element 2B is directly proportional to the level of violet light reflected by document D.

Measurement of the level of intensity of violet color light reflected by the document exposed to violet light This measurement is made by switching on a "super blue" LED 1 B. Part of the light emitted by the "super blue" LED 1 B passes through a light filter 3 (emission of light of purple color) and comes project onto document D. Part of the violet light is reflected LR2 by document D and passes through a light filter 6 towards the photosensitive element 2B.

• Measurement of the light level resulting from the fluorescence of the document exposed to purple light

This measurement is made by switching on a "super blue" LED 1 B. Part of the light emitted by the "super blue" LED 1 B passes through a light filter 3 (emission of light of purple color) and comes project onto document D. Part of the light is reflected LR1 by document D towards the photosensitive element 2A.

The electrical signals produced by the photosensitive elements 2A and 2B make it possible to determine the level of light emitted by the fluorescence of document D, by subtraction: electrical signal produced by 2A - electrical signal produced by 2B.

Measurement of the level of intensity of infrared light reflected by the document exposed to red and / or infrared light.

This measurement is made by lighting a red LED 1 D and / or infrared 1 E. The light S4 and / or S5 emitted respectively by the LED 1 D or 1 E is projected onto document D. Part of the light is reflected LR2 through document D to the photosensitive element 2A.

The placement of these measurement systems against the two sides of the document allows, in addition to the analyzes of the reflected light rays, to be able to make analyzes of the light rays (visible or not visible) transmitted through the document. Several types of measurement can be carried out by transmissions through the document of these various lights or rays.

The measurements made by transmitting, through the document, lights or light rays (visible or not visible) are:

• Measurement of the level of intensity of violet color light transmitted through the document exposed to violet light

This measurement is made by switching on a "super blue" LED 1 B. Part of the light emitted by the "super blue" LED 1 B passes through a light filter 3 (emission of light of purple color) and comes projecting onto document D. Part of the light is transmitted by document D and passes through a light filter 6 to the photosensitive element 2B of the measurement system located on the opposite face.

The electrical signal produced by the photosensitive element 2B is directly proportional to the level of violet light transmitted through the document

D.

• Measurement of the level of intensity of violet color light transmitted through the document exposed to blue light

This measurement is made by lighting a "super blue" LED 1A. Part of the light emitted by the "super blue" LED 1A is projected onto document D. Part of the light is transmitted through document D and passes through a light filter 6 to the photosensitive element 2B of the measurement system located on the opposite side.

The electrical signal produced by the photosensitive element 2B is directly proportional to the level of violet light transmitted through document D. • Measurement of the level of light intensity transmitted through the document exposed to visible light

This measurement is made by lighting a LED 1A and / or 1 C and / or 1 D of color present in the emitting cell (blue, and / or green, and / or red). Part of the light emitted by LED 1A and / or 1 C and / or 1 D is projected onto document D. Part of the light is transmitted through document D to the non-filtered photosensitive element 2A of the system located on the opposite side.

The electrical signal produced by the photosensitive element 2A is directly proportional to the level of light transmitted through document D.

This measurement makes it possible to know the level of visible light transmission power of the document. Indeed, certain paper used to prepare false documents, such as banknotes, can have similarities in terms of analyzes of violet light or ultraviolet rays.

However, these papers making it possible to obtain these similarities are most of the time of a different opacity generally due to a different grammage. The analysis of this opacity and therefore of the power of visible light transmissions of the paper makes it possible to obtain an additional criterion on the nature of the paper considered.

• Measurement of the level of intensity of infrared rays transmitted through the document exposed to rays of which part of their spectra or all are located in the infrared zone.

This measurement is made by lighting a red LED 1 D and / or an infrared LED 1 E of the transmitting cell. Part of the rays emitted by the LED 1 D and / or 1 E is projected onto the document D. Part of the rays is transmitted through the document to the unfiltered photosensitive element 2A (if an infrared LED 1 lights up E) or the photosensitive element 2D infrared (if a red LED 1 D and or infrared 1 E of the measurement system on the opposite side are lit).

The electrical signal produced by the photosensitive element 2A or 2D according to the lit LED, is directly proportional to the level of intensity of the infrared rays transmitted through the document.

Some types of paper react differently when they are subjected to infrared rays. In fact, experienced counterfeiters often coat the paper used to prepare their false documents with products that make it possible not to identify their false documents with ultraviolet rays. However, these papers, treated in this way, react differently to their exposure to infrared rays.

Similar methods are frequently found in counterfeit banknote detectors. However, these are used either to measure the reaction of the ink used on the banknote, or to detect the presence of a security metal wire (document GB2273353). The method and the device according to the invention make it possible to analyze the paper and not the ink or the presence of security threads.

The method for checking the authenticity of documents described above can advantageously be implemented in a portable and autonomous electronic device for detecting counterfeit banknotes, of small size supplied by battery or by the sector via a regulating block. external, automatically giving a "True", "Doubtful" or "False" indication of the controlled bank note.

This device is in the form of a small housing 10 (FIG. 1) which can easily be held in the hand. One of the faces of said device is provided with a transparent window 1 1 and intended to be pressed when using said device, on the white area of the ticket to be checked, placed on an opaque support O.

The internal structure of such a device is illustrated in Figure 18. This internal structure includes:

• a measurement stage

This stage brings together the different optoelectronic components 1A, 1B, 1C, 1 D, ..., and 2A, 2B, ..., previously described and making it possible to carry out the six authentication tests of the paper, namely:

- measurement of dirtiness or aging of the ticket;

- measurement of dirt and aging of the banknote;

- measurement of the level of intensity of violet color light reflected by the banknote exposed to blue light;

- measurement of the light intensity resulting from the fluorescence of the ticket exposed to violet light;

- measurement of the intensity level of violet color light reflected by the banknote exposed to violet light.

- measurement of the level of intensity of infrared light reflected by the ticket exposed to red and / or infrared light.

• a stage for shaping the measurement signals

This stage includes the electronic components and circuits known per se and allowing the shaping of the electrical signals coming from the measurement stage. The layout allows among other things:

- amplify the electrical signals

- to filter the electrical signals

- to clip the electrical signals

The controls of the various parameters of the stage of shaping of the measurement signals, such as for example the value of the gains of the amplifiers, the bandwidth of the filters, can be controlled by the UTANS. • an Analog-Digital Converter stage

This stage comprises the electronic components and circuits known per se and allowing Analog-to-Digital conversion of the analog electrical signals coming from the measurement stage or from the stage for shaping the measurement signals into digital signals transmitted to the stage. utans.

• a digital signal processing and analysis stage (UTANS)

This stage comprises the various electronic circuits and systems making it possible to control and / or analyze and / or store data coming from the stages:

- Analog to Digital converter

- shaping of the supply voltage

- shaping of measurement signals

- Human-Machine interface input

- measures

- memories

It also allows:

- to communicate bi-directionally, by means of a Computer-Machine interface, with a computer, in order to possibly change program parameters;

- to indicate by means of the output Human-Machine interface, information such as for example, the authentication of the ticket tested, as well as system parameters. UTANS can be made up of:

- a microprocessor;

- And or a microcontroller;

- and / or programmable logic;

- and / or a digital signal processing system (DSP)

• an input Human-Machine Interface stage

This stage includes an assembly allowing the user to communicate with the device by means of keys, accessible on the case of this one.

• an output Human-Machine Interface stage

This stage comprises the means or means making it possible to give the user data such as the authenticity of the ticket tested, as well as system parameters, by means, inter alia:

- indicator lights;

- and / or displays;

- and / or sound signals;

- and / or vibrators.

• a Computer-Machine Interface stage

This stage comprises the circuits known per se making it possible to communicate bi-directionally with a computer, for example in order to possibly change program parameters. • a memory stage

This stage comprises the memory or memories known per se making it possible to store information on volatile and / or non-volatile memories.

a supply voltage shaping stage

This stage includes an Analog-to-Digital converter enabling UTANS to be informed of the voltage level delivered by the power source, so that the latter stops taking measurements and warns the user of a possible voltage problem d 'food.

a voltage regulation stage

This stage is composed of a voltage regulator and a filtering, making it possible to provide a stable supply to the various circuits composing the internal electronic structure of the device.

• a feed stage

This stage provides a source of energy supplying the device. This energy source can consist of:

- batteries

- an external power supply

The device thus configured may also include circuits

testing the good condition of the battery; - testing the correct placement of the device against the ticket to be checked.

These tests are done automatically or manually during the document authentication procedure.

If the battery has too low a voltage level that could affect the proper functioning of the device, a measurement of this voltage level is low. If it has a voltage level below a stored constant, the device will automatically error and indicate to the user the problem, otherwise it follows its normal operating cycle.

One of the major drawbacks due to the use of semiconductor components is that the electrical characteristics of these components vary significantly at ambient temperature. In order to have comparable results whatever the ambient temperature, it is interesting to know the latter and to adapt the program parameters accordingly. Therefore the device can include a sensor taking the ambient temperature and thus after shaping and analog-digital conversion of the signal at the sensor output, the UTANS can adapt the program parameters according to the temperature drift of the electronic components .

Likewise, if the device is badly pressed against the banknote or if the bearing surface of the bill is not opaque, stray external light reaches the measurement receivers. In order not to distort the measurements, and therefore the result on the authentication of the ticket, the device measures and analyzes the level of light intensity at the level of the measurement window (all LEDs off). If this light level is greater than a stored constant, the device will automatically go into error and inform the user of the problem, otherwise it follows its normal operating cycle.

If all the tests are correct, the device starts the following measurement procedures:

• dirt and / or ticket aging measurements; • measurement of the level of intensity of violet light reflected by the banknote exposed to blue light;

• measurement of the light intensity resulting from the fluorescence of the ticket exposed to violet light;

• measurement of the level of intensity of violet color light reflected by the banknote exposed to violet light.

• measurement of the intensity level of infrared light reflected by the ticket exposed to red and / or infrared light.

Finally and before a notice on the authenticity of the ticket, the device again checks the correct plating of the device against the ticket, in order to check whether apparently the series of measurements carried out has been carried out in good conditions. Once all the measurements have been taken, the digital signal processing and analysis unit (UTANS) operates in order to indicate by means of the Human-Machine interface an opinion on the authenticity of the bank note tested. This could possibly be repeated as long as the user presses the device against the ticket and presses the button (see measurement algorithm figures 19A and 19B).

Claims

1.- Method for verifying the authenticity of documents, for example banknotes or checks, characterized in that the document (D) to be checked is successively exposed to several light sources (1A, 1 B, 1 C , 1 D, ...) consisting of optoelectronic components and each emitting a different light spectrum (S1, S2, S3, ...), the light rays (LR1, LR2, ...) emitted by these optoelectronic components and reflected by the document (D) and / or transmitted through it, by means of receptor cells constituted by photosensitive components (2A, 2B, ...) making it possible to convert the lights received on their surface sensitive to analog electrical signals transmitted to a processing unit (UTANS), after shaping and conversion into digital signals, said processing unit incorporating an algorithm and being configured and programmed to analyze the digital signals received and to transmit a result on the authenticity of the document checked.

2.- Method according to claim 1, characterized in that one determines, independently, by an analysis of the light rays reflected by the document exposed to a light source comprising inter alia a spectrum of light covering the band of wavelengths from 380 nm to 410 nm, the light intensity level being in a light spectrum covering the wavelength band from 380 nm to 400 nm (or even 410 nm) (purple light), reflected by the document and that the reflection power of the latter is thus determined in this same band of wavelengths.

3.- Method according to one of claims 1 or 2, characterized in that one independently determines, by an analysis of the light rays reflected by the document exposed to a light source of purple color (light spectrum covering the band of wavelengths from 380 nm to 400 nm (or even 410 nm) the level of light intensity lying in the visible spectrum, reflected by the document and which thus determines the level of fluorescence of the document.

Process according to any one of Claims 1 to 3, characterized in that the light rays reflected by the document exposed to a light source of violet color are determined independently (spectrum of light covering the band of lengths d waves from 380 nm to 400 nm (or even 410 nm) the light intensity level lying in a light spectrum covering the wavelength band from 380 nm to 400 nm (or even 410 nm) (violet light) , reflected by the document and that the reflection power of the latter is thus determined in this same band of wavelengths.

Process according to any one of Claims 1 to 4, characterized in that the level of soiling and / or aging of the document is determined by analysis of the light rays reflected by the document exposed to blue light. in order to modify the program parameters.

6.- Method according to any one of claims 1 to 5, characterized in that one independently determines, by an analysis of the light rays reflected by the document exposed successively to a light of blue color and a light of green color or to a blue light and a red light or to a blue light and a red light and a green light, the degree of soiling and / or aging of the document, in order to modify the program parameters .

7.- Method according to any one of claims 1 to 6, characterized in that one determines by an analysis of the infrared rays transmitted through the document and / or reflected by the document, the power of transmission and / or reflection of infrared rays, in order to detect the presence of possible paper treatments.

Method according to any one of Claims 1 to 7, characterized in that the light transmitting power of the document and therefore its opacity to visible light is determined by an analysis of the visible light rays transmitted through the document.

9.- Method according to any one of claims 1 to 8, characterized in that one determines by an analysis of the light rays, comprising inter alia a spectrum of light covering the band of wavelengths from 380 nm to 400 nm (or even 410 nm) transmitted through the document, the power of light transmission at the level of the wavelength band from 380 nm to 400 nm (or even 410 nm), and therefore the opacity of this document to this same band of wavelengths.

10.- Method according to any one of claims 1 to 9, characterized in that light-emitting diodes (LEDs) are used, with or without light filter, to obtain the various light sources having different spectra, and , more particularly, an LED usually called "super blue" color having an emission peak lying in the wavelength band from 400 nm to 450 nm, to obtain a light spectrum covering at least the band of 380 nm to 410 nm.

11. Method according to any one of claims 1 to 10, characterized in that constant current generators are used to supply the optoelectronic emitting components such as light-emitting diodes (1A, 1B, 1C, 1D, 1E).

12.- Apparatus for verifying the authenticity of documents, for example banknotes or checks, preferably executed in the form of a portable and autonomous apparatus, comprising a housing (10) one side of which is provided with a window transparent (11) intended to be pressed, when using the device, on a face of the document (D) to be checked, the internal structure of this device comprising a power supply, a measurement system grouping together the different optoelectronic components (1A, 1 B, 1 C, 1 D, ...) capable of generating light intended to be reflected by said document (D) and the photosensitive electronic components (2A, 2B, ...) capable of capturing the light reflected by the latter and / or passing through it and of transforming it into electrical signals, a processing unit ( UTANS) configured and programmed to analyze the electrical signals and issue a result on the authenticity or non-authenticity of the controlled document, and a signaling means enabling the user to be informed of the conclusion of this result, characterized in that optoelectronic light emitting components (1A,

1 B, 1 C, 1 D, ...) are constituted by light-emitting diodes, each emitting a different light spectrum (S1, S2, S3, ...), so as to allow at least two the following authentication tests:

- measurement of dirtiness or aging of the document;

- measurement of dirt and aging of the document;

- measurement of the level of intensity of violet color light reflected by the document exposed to blue light;

- measurement of the light intensity resulting from the fluorescence of the document exposed to violet light;

- measurement of the level of intensity of violet color light reflected by the document exposed to violet light;

13.- Apparatus according to claim 12, characterized in that the light emitting optoelectronic components (1A, 1 B, 1C, 1 D, ...) comprise at least one light emitting diode of "super blue" color (1A) of which the emission peak has a wavelength between 400 nm and 450 nm.

14.- Apparatus according to claim 13, characterized in that the "super blue" LED (1B) is provided with a light filter (3).

15.- Apparatus according to one of claims 13 or 14, characterized in that the light emitting optoelectronic components (1A, 1B, 1C, 1D, ...) comprise at least one green light emitting diode (LED) and / or red.

16.- Apparatus according to any one of claims 13 to 15, characterized in that the light-emitting electronic components (1A, 1 B, 1 C, 1 D, ...) comprise at least one light-emitting diode (LED) infrared (1 E).

17.- Apparatus according to one of claims 13 or 14, characterized in that at least one of the photosensitive receivers (2B) is provided with a light filter (6).

18.- Apparatus according to any one of claims 12 to 17, characterized in that it comprises a regulation cell (9) making it possible to regulate the level of light intensity emitted by the emitting optoelectronic components (1A, 1B, 1C , 1 D, ...).

19.- Apparatus according to any one of claims 12 to 18, characterized in that its internal electronic structure comprises a stage for shaping the electrical signals coming from the measurement stage, this shaping stage consisting of electronic components and circuits used in particular to: amplify, filter and clip said electrical signals.

20.- Apparatus according to any one of claims 12 to 19, characterized in that its internal electronic structure comprises an Analog converter stage- Digital consisting of electronic components and circuits allowing Analog-Digital conversion of analog electrical signals from the measurement stage or the signal shaping stage, into digital signals, transmitted to the processing and digital signal analysis (UTANS).

21.- Apparatus according to any one of claims 12 to 20, characterized in that the processing and analysis unit (UTANS) comprises, in particular: a microprocessor, and / or a microcontroller, and / or programmable logic , and / or a digital signal processing system (DSP).

22.- Apparatus according to any one of claims 12 to 21, characterized in that its internal electronic structure comprises a human-machine input interface stage, constituted by a mounting allowing the user to communicate with the apparatus at way of keys.

23.- Apparatus according to any one of claims 12 to 22, characterized in that its internal electronic structure comprises a memory stage comprising the memory or memories allowing to store information on volatile or non-volatile memories.

24.- Apparatus according to any one of claims 12 to 23, characterized in that its internal electronic structure comprises a computer-machine interface stage comprising the circuits for communicating bi-directionally with a computer.

25.- Apparatus according to any one of claims 12 to 24, characterized in that its internal electronic structure includes a voltage shaping stage power supply, this stage comprising, among other things, an Analog-to-Digital converter making it possible to inform the processing and analysis unit (UTANS) about the voltage level delivered by the power source, so that the latter stops taking measurements and notifying the user of possible supply voltage problems

- Apparatus according to any one of claims 12 to 25, characterized in that its internal electronic structure comprises a voltage regulation stage, this stage comprising a voltage regulator and a filter making it possible to supply a stable supply to the various circuits making up said circuit internal electronic structure

Apparatus according to claim 12, characterized in that its internal electronic structure comprises an ambient temperature measurement stage, this stage comprising at least one sensor making it possible to measure the ambient temperature in order to possibly adapt the program parameters

Apparatus according to claim 12, characterized in that one determines before and / or during and / or after the measurement phase, all light emitters of the measurement cell off, the light level at the level of the latter, in order to to check the correct plating of the device against the ticket