DE1911897A1 - Method and device for checking securities - Google Patents

Description

PATENT LAWYERS 4 DÜSSELDORF 1

Malkastenstrasse2 DIPL.-ING. ALEX STENGER

Telephone (0211) 360514 DIPL.-ING. WOLFRAM WATZKE

Our time: 1θΓ35 Date: - 7th MAR. 1969

Scheidt & Bachmann GmbH, 4o-7 Rheydt, Breite Strasse Γ32 Method "and device for checking securities

The invention relates to a method and a device for checking securities, in particular bank notes, in which the test specimen passed between a light source and a photoelectric converter and one of the proportion of the translucent light proportional voltage is generated.

The need to test securities arises on several occasions. For example, it is necessary to be able to check banknotes for authenticity during payment transactions in financial institutions. When producing banknotes, it is necessary to continuously monitor the print quality and to eliminate the rejects. Furthermore ea is required to check the authenticity of banknotes in currency exchange or Ve: to test automatic 3 s, so there is a real Ss Bedürfni: -l - · for a simple and reliable method for testing securities.

It is known that bank notes can be fed purely mechanically via the paper thickness or electrically to the presence of a metal thread check »It is also known to print banknotes with magnetic or fluorescent inks so that they can later be used in To be able to check business transactions for the presence of these characteristics. These known test methods have not been found I can enforce them because they cannot be applied to all banknotes and are not forgery-proof.

009838/0090

Photoelectric test methods are also known which the banknotes are illuminated or transilluminated so that the reflected or translucent portion of the Light can be evaluated for the test. Two methods can be used for these known photoelectric test methods can be distinguished.

According to the first method, those produced on a banknote are produced photoelectric measured values with those of a real banknote constantly present in the banknote validator compared.

According to the second method, those produced on a banknote are produced The photoelectric measured values then look for whether they are within predetermined tolerance values.

These known photoelectric test methods have not been able to establish themselves because they are too sensitive are. When used as intended, banknotes are not only worn out, they are also regularly soiled » After a while they can be wrinkled χ, thick, torn or glued back together., As with the known = th photoelectric test method measured in a pictorial manner becomes, the probability is very high * that in itself real banknotes as a result of their use = changes are classified as counterfeit banknotes »Such a misjudgment of the authenticity of a banknote can have a negative effect in an emergency, for example when purchasing urgently needed goods.

The invention has set itself the task of "simplifying the known photoelectric test method and improving it by changing from the previous pusfetf8s? Ailgen measurement to area measurement in terms of FeliltoGtsräeiiiang su. In the remainder there is the " invention ". "to eliminate the disadvantages of the Sfcß & slas. des? S®§liaite % n ",

'SAD ORIGINAL

"'■' OCTS8 38/0980 - - ■

? S.

Based on the known method for checking securities, in which the test object is passed between a light source and a photoelectric converter and a the proportion of the transmitted light is generated voltage proportional to the object underlying the invention solved in that by interference of the shining light on a grid and by the movement of the test specimen an alternating voltage with a certain frequency and high amplitude is generated at the photoelectric converter. These AC voltage can then be used in a resonance circuit selected and the resonance frequency processed in an amplifier to a useful signal.

On securities, especially banknotes, are for protection Fine parallel lines, so-called guilloches, or the drawing of the printed ones, are printed on to protect against forgeries Representation is composed of a large number of fine lines or rows of points. This peculiarity of the drawing The invention makes use of securities or banknotes. Through the interplay of fine lines or Rows of points with a grid arranged in the beam path can use the interference effect known per se for the evaluation the measurement result can be advantageously used. A particular "advantage is that the measurement is based on a wide and long area of the; banknote can be stretched out. This means that wrong decisions are as good as impossible, because the changes that occur when the banknote is used are generally those on which the measurement is based Do not make the entire surface unusable for the test. The surface examination also has the advantage that the the punctiform test procedures possible fraudulent maneuvers by inserting cut-out parts of real banknotes excluded are.

In a further embodiment of the invention, in a device for performing the method, which consists of a

009838/0090

Light source and a light-electric converter that Grid be arranged between the test object and the photoelectric converter. To reduce the interference effect for the To make the measurement result fully usable, it has proven to be useful proved the grid of lines in the drawing of the test item.

More details, features and benefits of the; ¹ the subject of the invention will become apparent from the following description check W bung of the accompanying drawing, in which a preferred embodiment of an apparatus for inspecting value ". papers is shown schematically. In the drawing show:

1 shows a schematic measuring arrangement;

Fig. 2 is a circuit diagram for the generation and evaluation of the Measurement result and the formation of a useful signal;

Fig. 3 and 4 :

two different mutual positions of a test object and a grid to explain the for the Invention of essential interference effect.

A test specimen 2, on the surface of which lines 3 are printed, is arranged above a light source 1. In the beam path of the light source 1, a grid 4 and a photoelectric converter 5 are arranged at a distance above the test object 2.

When moving the test item 2 to the grid 4 in the direction of movement χ alternate between the positions shown in Figures J and. In the case of the one shown in FIG

'The mutual position of test item 2 and grid 4 are the weak or unprinted areas of the test object 2 and the openings of the grid 4 are arranged congruently one above the other, so that the light rays β directly into the light elec-

. tric converter 5 can occur. In the case of the FIG shown mutual position of test item 2 and grid 4.

009838/0090

the weakly or unprinted areas of the test object 2 are covered by the lines of the grid 4, so that no light rays β can enter the photoelectric converter 5. In the exemplary embodiment shown, the photoelectric converter 5 consists of a photodiode which has a very small resistance R when light falls and a very high resistance R when it is darkened. As a result of the movement of the test specimen 2 under the grid K and the associated change between lightness and darkness, a Viechs el voltage of a certain frequency is generated across the photoelectric converter.

FIG. 2 shows a circuit diagram in which a direct voltage from a current source 7 is applied to the photoelectric converter 5. With the current source 7 and the photoelectric converter 5 are connected in a 9 kompexer resistor 8 and a Kodensator i ⁿ row (8,9) together forming a series resonant circuit. Furthermore, the base-emitter path BE of a transistor Io is connected in series. The collector C of the transistor Io is connected to the positive pole of the current source 7 via a resistor 11. In this circuit diagram, a useful signal 15 is present at terminals 12.

When the test object 2 moves, the photoelectric converter 5 periodically changes its resistance R. If the frequency the resulting alternating voltage corresponds to the resonance frequency of the oscillating circuit (8, 9), this oscillating circuit becomes low resistance, so that the transistor Io turns on and on the useful signal Ij5 is present at terminals 12. The useful signal I3 means that the test was positive.

All mentioned in the description and shown in the drawing New features are essential to the invention, too as far as they are not expressly claimed in the following claims. ■

009838/0090 ^BAD

Claims (4)

Expectations: 1. Procedure for checking securities, in particular Banknotes in which the test item is between a light source and a light-electrical converter and a voltage proportional to the amount of light shining through is generated, characterized, } that by interference of the light shining through a grid (4) and an alternating voltage due to the movement of the test object (2) on the photoelectric converter (5) is generated with a certain frequency and high amplitude. 2 .. The method according to claim 1, characterized in that the alternating voltage is selected in an oscillating circuit (8, 9) and the resonance frequency in an amplifier (transistor Ioj resistor 11) processed into a useful signal (1 ^) will. ■ J5. Device for performing the method according to the ^ Claims 1 and 2, consisting of a light source and a 3-i dielectric transducer, characterized in that that the grid (4) is arranged between the test item (2) and the photoelectric converter (5). 4. Apparatus according to claim 3 *, characterized in that the grid (4) is adapted to the lines of the test object (2). ^c