WO2011114266A2 - Method for coding and decoding an electronic code and relative electronic code - Google Patents

Abstract

An electronic code (1a;1b;1c;1d) is described which comprises a plurality of elements (3), each of said elements (3) being representative of a piece of information and said elements being so arranged as to form a sequence, wherein said elements (3) can be obtained through at least a first substance having a first conductance value and a second substance having a second conductance value, different from said first conductance value.

Description

METHOD FOR CODING AND DECODING AN ELECTRONIC CODE AND RELATIVE ELECTRONIC CODE

DESCRIPTION

The present invention relates to the field of methods for coding and decoding an electronic code.

More in particular, the present invention relates to an electronic code, to a method for increasing the information density of an electronic code, and to the relative electronic code.

Electronic codes are known in the art which are applied to an object so that it can be identified and/or tracked.

International patent application No. WO 2009/138571 discloses a method for generating an electronic code by exploiting the electric properties of inks, so as to make the electronic code more difficult to clone or copy.

Cloning an electronic code means to print a code without knowing the logic that generates it; copying an electronic code means to print an electronic code when the generation logic thereof is known.

According to the above-mentioned patent application, the code is read by analysing how a surface containing electronic codes printed in accordance with said method reacts to radio frequency.

International patent application No. WO 2009/138571 describes an electronic circuit built in a scanner which is used for disassembling into a real component and an imaginary component the current generated within the ink by radio-frequency excitation. Electrodes are used to supply an alternating (or anyway non-constant) electric signal to the electronic code and then, again by using said electrodes, the response current or voltage is measured.

Compared to other radio-frequency electronic code scanning systems, the method described in the above-mentioned international patent application ensures a more reliable scan, thanks to the quality of the signal provided by analysing the conductive properties of the ink and to the capability of obtaining said signal even when the code is scanned without contact, i.e. on the back side of the substrate whereto the electronic code has been applied, or through a graphic decoration layer or a protection layer protecting the code against external agents. International patent application No. WO 2009/138571 describes a technique for generating a code commonly called "postal code" and consisting of a series of bars arranged vertically with respect to the code scanning direction.

All printed bars have the same electric properties and the same width.

The number of bars required for describing a piece of information is equal to the number of bits of that piece of information plus one bar representing a control code.

An electronic code 1 using the teachings of international patent application No. WO 2009/138571 is shown by way of example in Fig. 1.

It comprises a sequence of elements 3, in particular vertical bars, having a single electronic property and drawn by using the same ink.

The digital information contained in the electronic code is determined by the distance between the bars. If the space following a vertical bar is short, that vertical bar will be considered to represent, for example, a zero value bit, whereas if the space following a vertical bar is long, then the vertical bar will be considered to represent, for example, a one value bit. Based on this definition, the code of Fig. 1 corresponds to the binary representation of the bit sequence "000010010000100100001001 10111000".

However, such an electronic code has at least two drawbacks:

- information density, i.e. the ratio between the quantity of bits and the number of bars in the electronic code, is relatively low;

- the content of the electronic code is optically visible and therefore, when the electric property of the ink is known, the electric code is relatively easy to clone.

In order to improve the security of an electronic code, the latter problem can be overcome by using inks which are difficult to see and/or hidden under graphics, but it is not always possible to formulate transparent inks having well-defined electric properties, such as conductivity.

Codes are also known which exploit other physical properties of inks. Nonetheless, exploiting these properties poses technological and economical limits, or is not applicable to the anti-counterfeit field because the code obtained can be copied easily. For example, one may use inks of different colours and attribute a different piece of information to each colour. However, the electronic code obtained with this technique is easily clonable and its scanning techniques are complex and sometimes not very reliable. It is therefore one object of the present invention to provide a method for increasing the information density of an electronic code and a relative electronic code. It is another object of the present invention to provide a method for generating an electronic code so that it is extremely difficult to copy or clone.

It is a further object of the present invention to provide a method for generating an electronic code which can be reliably scanned.

These and other objects of the invention are achieved by the method for coding and decoding an electronic code and the relative electronic code as claimed in the appended claims, which are intended as an integral part of the present description.

In short, the present invention describes a method for generating an electronic code that contains information which can be decoded by analysing the electric properties of at least two substances that the elements of the electronic code are made of.

In particular, the electric property of the substances may be their electric conductivity, expressed in mathematical form as the real part and the imaginary part of conductance. Any substance used for generating the electronic code may be specifically characterised through an electric property thereof, and this allows to increase the density of the information associated with each element of the electronic code.

The analysis of the electronic code according to the invention is not limited to detecting the presence or absence of the substances making up the code itself, since it also detects the electric properties thereof; therefore, each element of the electronic code can store more than one information bit, unlike when only the presence or absence of the electronic code substance is analysed.

For example, assuming that there are two inks having distinct electric properties, referred to as A and B, an electronic code may be made up of bars printed with a sequence of said inks A and B, wherein each letter indicates one bar printed with said inks, e.g. "ABBAABABBBAA".

If the number of inks used for generating the electronic codes is increased to four, referred to as A, B, C, D, the same information may, for example, be contained in the sequence "CDCCBA".

As can be seen, the four- ink code contains a number of bars which is 50% less than that of the two-ink code, hence it has double information density.

The electronic codes generated in accordance with the invention are also extremely difficult to clone because, if they cannot be distinguished through other physical properties (e.g. colour), it is not possible to discern the sequence arrangement without specifically knowing the technique and using advanced analytical equipment. The electronic codes generated in accordance with the invention are thus particularly difficult to clone and virtually impossible to copy.

Further features of the invention will be set out in the appended claims, which are intended as an integral part of the present description.

Said objects will become more apparent from the following detailed description of the method for coding and decoding an electronic code and the relative electronic code, with particular reference to the annexed drawings, wherein:

- Fig. 1 shows an electronic code according to the prior art;

- Fig. 2 describes the electric behaviour of various types of ink;

- Figs. 3a-6a show some didactic examples of electronic codes according to the invention;

- Figs. 3b-6b show some actual examples of electronic codes according to the invention. Referring now to Fig. 2, there is shown a graph representing the electric behaviour, in particular the conductance value Y, of a plurality of inks when they are subjected to an alternating or anyway variable electric field.

Each type of ink used has a different electric behaviours. A scanner capable of discerning the various electric behaviours of conductive inks making up an electronic code has been described, for example, in international patent application no. WO 2009/138571.

By way of example, the Applicant has developed inks and printing techniques which can generate electronic code elements having well-defined electrically conductive behaviours: inks Z having insulating conductive behaviours; inks A of the purely real type (in phase with the radio frequency excitation); inks B of the purely imaginary type (out of phase by +90° or -90° with the radio frequency excitation); inks C of the mixed type (having a real component and an imaginary component, both non-null), obtainable by mixing together inks of the A and B types.

C-type inks are virtually infinite, just like A-type and B-type inks.

The use of these inks creates very stable electric behaviours of the elements of an electronic code and allows to develop software capable of interpreting sequences of elements forming the electronic code even in the presence of very poor operating conditions or very degraded quality.

Furthermore, the coding can be made independent of the quantity of deposited ink, in that the code decrypting process does not use the variable of the absolute amplitude of the electric signal (meaning the amplitude of the real and imaginary components), but the presence/absence of a signal and the ratio between the imaginary part and the real part.

In this regard, the Applicant has modified the firmware of a scanner created for scanning the prior-art electronic code 1.

This firmware modification involves the simultaneous analysis of both the real and imaginary components of conductance, instead of simply analysing the real component only or the two components' module. Thanks to this modification, it is possible to classify the bars as A, B, C and Z depending on the ratio between the real component and the imaginary component of conductance. Subsequently, a logic which is inverse to the one used for the encrypting process allows the code content to be deciphered.

It is clear that the larger the number of inks used, the harder it becomes for a counterfeiter to clone or copy an electronic code created in accordance with the invention.

There is no maximum limit to the number of usable inks, since the only physical limitation is the scanner's resolution capability.

Referring now to Figs. 3a to 6a, and assuming that one wants to code the aforementioned sequence "00001001000010010000100110111000" containing 32 information bits, the following will illustrate four possible embodiments of an electronic code according to the invention.

Note that Figs. 3a-6a are only meant to facilitate the comprehension of the invention, the actual electronic codes according to the invention being those shown in Figs 3b-6b. First embodiment.

With reference to Figs. 3a and 3b, assuming that, in order to generate an electronic code la, A and Z respectively designate an ink and an electrically neutral or insulating ink (also called "auxiliary ink"), and that a zero value bit is printed with an ink bar A and a one value bit is printed with two bars, the first one with ink A and the second one with ink Z (the distance between the bars always being constant), the result of the coding of the aforementioned binary representation "00001001000010010000100110111000" will be a sequence of elements consisting of inks having the following chemical composition:

AAAAAZAAAZAAAAAZAAAZAAAAAZAAAZAZAAZAZAZAAA+A for a total of 42 bars made of two ink types, with the addition of a final control bar, designated "+A", which is generally necessary for handling a logic in the decryption processor. As a matter of fact, since the scanner generally cannot discern between the electric properties of the substrate and those of the ink of the bar Z, it is necessary that the last bar is followed by a control bar, otherwise it would be impossible to know if the code ends with a "0" or a " 1 ".

Although not more compact than the prior-art electronic code, the electronic code la is more difficult to clone because it is obtained by using optically undistinguishable inks. In this regard, the dashed lines are used only for explanatory purposes to indicate an element 3' created with a Z-type ink, i.e. an insulating ink.

Second embodiment.

With reference to Figs. 4a and 4b, this embodiment uses, in order to generate an electronic code lb, a first and a second inks A, B (or C) and a third ink Z, which is insulating and therefore not detectable by the scanner, but optically visible. Said ink Z may possibly be replaced with an empty space.

For explanatory purposes only, the second ink B is represented by a series of crosses and the third ink Z is represented by a dashed line.

For example, assuming that "000" equals "A A", "010" equals "AB", "100" equals "AZ", "001" equals "BA", "011 " equals "BB", "101" equals "BZ", "110" equals "ZA" and "1 11" equals "ZB", the result of the coding of the digital sequence "000010010000100100001001 101 11000" will be a sequence of elements 3 consisting of inks having the following chemical composition:

AAABABAAAZAZBABABZZAAA+A

for a total of 22 elements plus a control bar, designated by the symbol "+A". Compared to the prior-art electronic code, which only uses one ink and one empty space, a reduction by about 55% of the number of elements 3 is obtained, as can be clearly inferred by comparing Fig. 1 with Fig. lb.

In this case it is possible to generate electronic codes lb having constant pitch and length and the same information density, which leads to advantages in terms of code security and graphics.

Cloning the electronic code lb becomes extremely difficult because both the A-type ink and the B-type ink have electric properties that can only be discerned by using a circuit like the one described in international patent application no. WO 2009/138571.

Third embodiment. With reference to Figs 5a and 5b, an electronic code lc is coded by using two inks, designated A and B, respectively, and a third ink designated Z, which is insulating and therefore not detectable by the scanner, but optically visible (same number of inks as in the second embodiment). Said auxiliary ink Z may possibly be replaced with an empty space.

For example, assuming that "00" corresponds to A, "01" corresponds to A followed by Z, "10" corresponds to B, and "11" corresponds to B followed by Z, the result of the coding of the sequence "0000100100001001000010011011 1000" will be a sequence of elements consisting of inks having the following chemical composition:

AABAZAABAZAABAZBBZBA+A

for a total of 20 elements plus a control bar, designated by the symbol "+A".

Compared to the prior-art electronic code, which only uses one ink and one empty space, a reduction in length by approx. 50% is obtained.

This technique does not allow to simultaneously obtain a constant pitch and a constant length, but information density is statistically higher than in the case shown in the second embodiment.

Fourth embodiment.

With reference to Figs. 6a and 6b, an electronic code Id is coded by using four inks, respectively designated A, B, C and Z, wherein, for explanatory purposes only, ink C is represented by a thicker dashed line than ink Z.

For example, assuming that "00" equals A, "01" equals B, "10" equals C, and "11" equals Z, the result of the coding of the sequence "00001001000010010000100110111000" will be a sequence of elements consisting of inks having the following chemical composition:

AACBAACBAACBCDCA+A

for a total of 16 elements plus a control bar, designated by the symbol "+A".

Compared to the prior-art electronic code 1, which uses only one ink and one empty space, a reduction in length greater than 60% is obtained, with the additional advantage that the number of elements 3 is constant.

The coding provided by this fourth embodiment allows to obtain a constant pitch and a constant length at the same time.

The electronic code Id is significantly shorter than the codes la, lb and lc, and contains a number of inks such that it becomes extremely difficult to clone. In the electronic codes lc and Id according to the invention it is possible to store much information in a quite short sequence, in that the information is contained not only in the geometrical arrangement of the elements 3 of the electronic code lc,ld, but also in the electric properties thereof.

Since all the elements 3 of the electronic codes la,lb,lc,ld may have the same colour, it becomes extremely arduous to clone such electronic codes la,lb,lc,ld.

The electronic codes la, lb, lc and Id may also be transparent.

The four above-described embodiments should be considered as mere explanatory examples, since many other embodiments may be conceived as well. What is important is to ensure logic biunivocity, i.e. a predetermined sequence read by a scanner must return exactly the same sequence of "0" and "1" that generated that predetermined sequence.

The coding must be chosen as a function of the limitations of the adopted scanning technique and printing technology.

For example, by using three inks and the coding technique described in the fourth embodiment, the Applicant has succeeded in printing, by means of an ink-jet printer, electronic codes Id as small as 75 mm or less and containing 40 bits of useful information in addition to security redundancies (which take approx. 30% of the available space), whereas with the prior-art coding technique of Fig. 1 , which uses only one ink and one empty space, a minimum area of approx. 300 mm was required, the printing resolution and scanner dimensions being equal.

The above-mentioned examples have clearly illustrated the method for increasing the information density of an electronic code comprising the following steps:

a) associating one or more symbols with a plurality of substances having respective different conductance values;

b) representing a sequence of elements graphically by using a plurality of substances in accordance with the association of step a), said sequence of elements forming said electronic code.

The corresponding method for decoding the electronic code thus generated comprises the following steps:

c) analysing, by means of a suitable scanner, each element of the electronic code as to the conductance value of the substance it is made of;

d) associating each element of the electronic code with a respective symbol or group of symbols according to the logic used during the coding process.

The electronic codes generated in accordance with the invention may be optically undistinguishable from one another, except for the non-constant number of elements of the above-described second embodiment.

The substance used for creating the electronic code of the invention may be, for example, printed onto a surface by means of a traditional ink-jet printer, the cartridges of which contain substances, in particular inks, having suitable conductance values.

The code may also be printed by using many other printing apparatuses using different printing techniques, among which, by way of example, flexographic printing, offset printing, rotogravure printing or thermal transfer printing.

The features of the present invention, as well as the advantages thereof, are apparent from the above description.

A first advantage of the present invention is that the electronic code according to the invention has higher information density than any prior-art electronic codes, while at the same time making copying and cloning more difficult.

A second advantage of the present invention is that the technique used for characterising the substances is extremely reliable because it is independent of the quantity of deposited substance and substrate quality. In fact, ink classification is only related to the value of the ratio between the real component and the imaginary component, not to the conductivity module or the absolute value of the single components.

Another advantage of the present invention is that the scanning of the electronic code according to the present invention is extremely reliable.

A further advantage of the present invention is that the code can be read by using a scanner identical to the one that contains the circuitry described in patent WO 2009/138571.

The method for coding and decoding an electronic code and the relative electronic code described herein by way of example may be subject to many possible variations without departing from the novelty spirit of the inventive idea; it is also clear that in the practical implementation of the invention the illustrated details may have different shapes or be replaced with other technically equivalent elements.

For example, the electronic code described herein comprises a series of elements in the form of vertical bars. However, such elements may also be represented as dots or curved lines. For example, the electronic code described herein is formed by a series of elements made of ink. However, other substances may be used which have distinct conductance values, such as, for example, a coating material or textile threads or another material having controllable electric properties.

It can therefore be easily understood that the present invention is not limited to a method for coding and decoding an electronic code and to the relative electronic code, but may be subject to many modifications, improvements or replacements of equivalent parts and elements without departing from the inventive idea, as clearly specified in the following claims.

Claims

1. An electronic code (la;lb;lc;ld) comprising a plurality of elements (3), each of said elements (3) being representative of a piece of information and said elements being so arranged as to form a sequence, characterised in that said elements (3) can be obtained through at least a first substance having a first conductance value and a second substance having a second conductance value, different from said first conductance value.

2. An electronic code according to claim 1, wherein said elements (3) are bars, lines or dots.

3. An electronic code according to claim 1, wherein said substance is: an ink; a coating material; a textile thread; a material having controllable conductivity.

4. An electronic code according to claim 1, wherein said piece of information comprises one or more information symbols.

5. An electronic code according to claim 1, wherein said elements (3) are all of the same colour.

6. An electronic code according to claim 1, wherein said elements (3) are transparent.

7. An electronic code according to claim 1, wherein the conductance of said substance has one of the following behaviours: insulating; purely real; purely imaginary; with a real component and an imaginary component, both non-null.

8. A method for increasing the information density of an electronic code, comprising the following steps:

a) associating one or more symbols with a plurality of substances, in particular inks, having respective different conductance values;

b) representing a sequence of elements (3) graphically by using a plurality of substances in accordance with the association of step a), said sequence of elements forming said electronic code.

9) A method for decoding an electronic code, comprising the following steps:

c) analysing, by means of a suitable scanner, each element of the electronic code as to the conductance value of the substance it is made of, in particular ink;

d) associating each element of the electronic code with a respective symbol or group of symbols according to the logic used during the coding process.

10. A printing apparatus adapted to reproduce the electronic code graphically in accordance with one or more of claims 1 to 7.