EP1458576B1 - Value document - Google Patents

Abstract

The invention relates to a sheet-shaped value document, such as a bank note. An authenticity feature which can be reliably verified by machine or by humans and which can moreover not be deceptively imitated by copying technology is realized by an electro-optical and/or acoustic display device integrated in the value document.

Description

The invention relates to sheet-shaped value documents, such. Paper money.

Although the invention is not limited to particular types of sheet-shaped value documents, the particular problem of banknotes will be discussed below by way of example. Banknotes are usually printed in order to permanently identify information that is particularly relevant to the circulation of the banknotes, such as the denomination and the issuing central bank. As machine-readable security elements, the banknotes usually have different ones, e.g. magnetic, electrical, luminescent, e.g. fluorescent feature substances. In order that the human being can check the authenticity of banknotes without the help of machines, tactile or visually verifiable authenticity features such as intaglio structures, watermarks or optically variable ones are also used. holographic elements integrated into the banknote.

In EP 0 905 657 A1 a banknote with an identification and / or authentication element is described, which consists of an integrated circuit that can securely save in electronic form accessible from outside information such as the value, the serial number, the publisher or the date of issue of the bill.

In WO 00/07151 A1 there is described a security paper and a method and apparatus for checking the authenticity of records recorded thereon. To increase the counterfeit security of securities, for example Banknotes, a security paper is used, in which an electronic circuit is embedded. For authenticity testing, a carrier-frequency input signal is transmitted to the circuit and an output signal, which is an authenticity feature, emitted by the circuit in response thereto is detected. Alternatively, the security paper may have an authenticity feature-having electro-optical surface area whose light reflection or transmission properties can be controlled as a function of an electrical voltage applied to the surface area. In the authenticity check, the control voltage is applied to this surface area.

In WO 00/50249 A1 For example, a security document such as a security or identity card is described with a security element having an optically variable material. This optically variable material imparts different color impressions at different viewing angles. In addition, the security element has at least one machine-readable feature substance which does not impair the visually visible, optically variable effect of the optically variable material.

In relation to this prior art, the object of the present invention is to provide such sheet-shaped value documents with new authenticity features that are particularly safe verifiable by humans.

This object is achieved by the value document according to claim 1. Advantageous embodiments and further developments are the subject of the dependent claims.

The present invention is based on the idea of providing value documents with an electro-optical and / or acoustic reproduction device which can visually and acoustically reproduce an information content. These electro-optical or acoustic reproduction devices, which are also referred to below as short (optical) displays or sound transmitters, can be used individually or in combination, e.g. a self-luminous optical display which radiates in the visible, infrared and / or UV spectral range and / or a non-self-illuminating optical display and / or display of electronic paper and / or an LCD and / or an LED and / or an electroacoustic sound transmitter and / or have a reciprocal piezoelectric sound transmitter and / or a magnetostrictive sound transmitter. The visual display can be a two-dimensional display area, e.g. in the form of an LCD or also an approximately punctiform light source, such as e.g. have a single LED. By electronic paper can be understood in a known manner, for example, a flexible substrate with embedded between electrodes controlled rotatable or displaceable microcapsules.

An advantage of such electro-optical and / or acoustic reproduction devices is that they represent an authenticity feature that can easily be verified by humans, and that, moreover, can not be deceptively imitated in terms of copying technology. In addition, these reproduction devices can preferably also be used as a machine-readable security, ie authenticity feature. Thus, for example, an associated bank-note processing machine may comprise a sensor device which, if appropriate upon excitation of the reproduction device through the machine, detects the optical or acoustic signals reproduced by the banknote and compares them with the measurement signals to be expected for genuine banknotes.

Associated banknotes will then be particularly secure automatically or by humans, without the aid of other tools, detect when the playback state of the playback device changes over time. In the simplest case, this may be that the playback is only temporary. This can be done by the fact that the display device, in particular by an external power source, for example by means of a photocell or by an inductive coupling, is supplied with power and lights only when a supply of energy or sends sound signals. Since a permanent sound reproduction in banknotes would have a disturbing effect, in this case the variant is particularly preferred that the reproduction takes place only when an external energy supply.

In contrast to this termination of playback when the external power supply is interrupted, it is advantageous for the display device to have an interface for signal control of the display device, in particular optically and / or electronically, which according to the invention is connected via a signal line to a control device integrated in the value document is that can change or change a reproduction state of the reproduction device in a timely manner.

In this case, regardless of the power supply, the reproduction state can be changed in a predetermined manner. The time to a change can be set, for example, as random or at one or more specific times or as happening in defined time intervals. A particularly simple example of this is a flashing display, such as a flashing dot-shaped LED, at predetermined time intervals lights. The associated control data are preferably stored in a memory of the control device.

Furthermore, not only the reproduction state can be changed, for example, by changing the brightness or volume of the reproduction device, but also the reproduced information content itself can be temporally changed. This can e.g. indicate that the sound transmitter plays different reproduction frequencies or frequency sequences or, in the case of a two-dimensional display surface, different display patterns, such as e.g. Characters or symbols. In order to facilitate the optical or acoustic differentiation of banknotes of different denominations, it may be provided that the display states for different denominations, e.g. differentiate by different sound frequencies or flares.

According to a further preferred embodiment, the display is used as an information or advertising space on which information is displayed. In particular, a purpose for the document of value can be displayed. In this case, the use of the bill is not completely free, but a particular use, such as the purchase in certain shops or of certain goods is considered preferred or limited or excluded. This display of the purpose can be mandatory or only as a recommendation. Furthermore, for example, testing devices set thereon can refuse the acceptance of such value documents for the payment of goods excluded by the display. The fact that the information about the intended use are reproduced visually visible, can be immediately recognized when circulating the money without additional aids, whether the banknotes are released for a particular use.

In this connection, it is possible that a shop e.g. his logo by writing corresponding data in the electronic memory of the display can be displayed and the banknotes so marked accepted as a discount coupon when buying. For a banknote with a nominal value of € 100, the customer would Goods worth 110 € received. If the store does not want to reissue the coupon banknote, it will then delete the displayed information identifying the coupon; by e.g. corresponding control signals are transmitted to the control device of the banknote.

Advantageously, the display can also be used to indicate the current validity of a banknote. It is conceivable, for example, that in the memory of the control device integrated in the banknote, a code can be written by authorized banks, which completely limits the use of the banknote, i. makes the note temporarily or permanently invalid. This condition will be recognized by associated readers for such banknotes and then the banknotes will be classified as non-genuine. In order to be able to recognize this invalidity without a reader, the validity status is also shown on the display. In this case, e.g. already an LED in the banknote, which is turned on or off in an invalid bill.

The optical display is preferably made of an electronic paper so as not to impair the flexibility of the mostly paper-produced banknotes.

It should be emphasized that the data in the memory according to the invention are encrypted and / or password protected to ensure that the data controlling the playback can only be changed by authorized writers and / or persons.

Fig.1

in schematischer Weise eine Banknote nach einem ersten Ausfüh- rungsbeispiel, mit einer optischen Anzeige in einem ersten Wiedergabe- zustand;

Fig. 2

die Banknote nach Fig.1 in einem zweiten Wiedergabezustand;

Fig. 3

in schematischer Weise eine Banknote mit einer optischen Anzeige nach einem zweiten Ausführungsbeispiel;

Fig. 4

in schematischer Weise eine Vorrichtung zur Bearbeitung von Bankno- ten;

Fig. 5

in schematischer Weise eine Banknote mit einem Schallsender nach einem dritten Ausführungsbeispiel;

Fig. 6

in schematischer Weise eine Banknote mit einem Schallsender nach einem vierten Ausführungsbeispiel; und

Fig. 7

in schematischer Weise eine Vorrichtung zur Bearbeitung von Bankno- ten.

Hereinafter, further embodiments and advantages of the present invention will be explained and described in more detail with reference to the accompanying drawings. The show

Fig.1

schematically a banknote according to a first embodiment, with an optical display in a first reproduction state;

Fig. 2

the banknote after Fig.1 in a second playback state;

Fig. 3

schematically a banknote with an optical display according to a second embodiment;

Fig. 4

schematically a device for processing banknotes;

Fig. 5

schematically a banknote with a sound transmitter according to a third embodiment;

Fig. 6

schematically a banknote with a sound transmitter according to a fourth embodiment; and

Fig. 7

schematically a device for processing banknotes th.

The FIG. 1 shows a banknote 1 according to a first embodiment. The banknote 1 has, among other things, a security thread 2, which is integrated in the banknote paper, as a security element. In addition, in banknote paper 1 designed as a chip 4 integrated circuit is introduced, as for example in the EP 0 905 657 A1 is described. The metallic security thread 2 acts as an open dipole antenna, via which data and / or energy are sent contactlessly from an external device to the chip and / or emitted by the chip 4. The chip 4 comprises a memory, not shown, for storing data. It may be, for example, a pure memory chip (ROM), a rewritable chip (EPROM, EEPROM) or a microprocessor chip.

The banknote 1 is distinguished in that it comprises an LCD display 5. The LCD display 5 can be incorporated with known thin-film technologies in the banknote paper 3 or applied to this. The display 5 is connected via an integrated in the paper 3 electrical signal line 6 with an interface of the chip 4, not shown. This connection 6 is used to control the display 5 in a manner which will be described in more detail below. The chip 4 is also still connected via a further signal line 7 with a photovoltaic cell 8, called "photocell" 8 for short. The photocell 8 serves to supply the chip 4 and the display 5 with irradiation with energy. It is shown the case that the chip 4 is present as a separate unit in another area of the paper 3 as a display 5 or photocell 8. Alternatively, the chip 4 but also in the display 5 or the photocell 8 itself be integrated. The power supply must not necessarily be done by means of a built-in paper 3 photocell. Alternatively or additionally, the dipole antenna 2 can also be used for contactless inductive energy input from the outside.

In known manner, the LCD display 5 has a display surface, which consists of a matrix of pixels, each associated with a pair of electrodes, so that by applying an electrical voltage to the associated electrodes optionally the individual pixels can be activated to a given pattern 16 a on the display 5, as shown in the FIG. 1 is shown as an example. The displayed patterns 16a can be eg texts and / or symbols. The use of symbols, such as pictograms, is hereby preferred because of the small dimensions of the display surfaces in the order of a few centimeters, since the reading of texts can be difficult because of the therefore necessary small font sizes.

The display 5 may in this case be designed so that a power supply to maintain a current state of the display is necessary, the pattern 16a is therefore displayed only when the display 5, by illuminating the photocell 8 is supplied with light, with power. Alternatively, it is also conceivable that the pattern 16a is permanently displayed and the power supply by means of the photocell must be present only if the displayed pattern 16a is to be changed over time, since for the transmission of the changed control signals from the chip 4 to the display 5 electrical current is needed.

Regardless of whether the displayed pattern 16a is displayed only when the photocell 8 is illuminated or permanently, the display 5 can either be designed in such a way that only a single, fixed pattern 16a is always displayed or the displayed pattern changes over time , FIG. 2 shows, for example, the display 5 of FIG. 1 in a second operating state in which a changed pattern 16b is displayed.

Due to the fact that the display 5 does not always display only a fixed, but alternating pattern, a security feature is realized that is visually particularly conspicuous and can not be faked by conventional copying and printing techniques.

By way of example, the case is described that the display 5 in energy supply from the outside, for example by means of the photocell 8, in as constant predetermined time intervals between these two reproduction states, ie the patterns 16a and 16b switches. The control signals for switching the display 5 are stored in a memory area of the chip 4, which controls the display via the signal line 6 according to these control signals in time. Since it is not important in this embodiment to change the switching characteristic of the display 5 over time from externally controlled, the associated memory area is preferably designed as not to be described memory in the only before the issue of the banknotes 1 once data about the desired and non-changing display properties are entered. Due to the fact that the memory area can be described only once, therefore, an undesirable change or manipulation of the playback states can be prevented.

If the display 5, as described in the previous case, used as an authenticity feature that is operated by switching between two or more states, this configuration can be particularly easily realized by a punctiform display, such as a flashing LED 5 'as they in the banknote 1 'according to the second embodiment of the FIG. 3 is integrated. Also in this case can be dispensed with a control of the chip 4 from the outside. For this reason, unlike the embodiment of the Figures 1 and 2 Furthermore, it is not absolutely necessary to provide an antenna for driving the chip 4. The chip 4 is therefore not integrated in the optional security thread 2 of the banknote 1 ', ie the security thread 2 has been inserted into the banknote paper 3, without being connected to the chip 4 as a dipole antenna. This leads to a simplified construction of the banknote.

As mentioned, equipment with a chip antenna 2 will only make sense if the display state of the display 5, 5 'is to be changed from the outside by changing the memory contents of the chip 4 by an external writing device. In this case, associated control data is preferably contactless via an inductive coupling of an antenna of the writing device to the antenna of the banknote, such as e.g. the dipole antenna 2 of the banknote 1.

An example of such a writing device 10 is shown in FIG FIG. 4 , The apparatus 10 comprises by way of example an input compartment 11 for banknotes 1, a writing device 12 with a transmission antenna 15 for the contactless, inductive transmission of data transmitted from the antenna of the chip 4 into the compartment 11 inserted banknotes 1 are received, a keyboard 13 as a control unit 13 for controlling the transmission process and an associated monitor 14 on which, inter alia, information about the data to be entered into the chip can be displayed. Through the keyboard, we are inputted by an operator, in which way the display state of the display 5 is to be changed, ie how, for example, the switching characteristic is to be changed when changing between different display states. Associated control data are then transmitted via the transmitting antenna 15 contactlessly by means of an inductive interaction to the antenna 2 of the chip 4. On the basis of the signals received by the antenna 2, a data content of the memory of the chip 4 is subsequently changed, which leads to a change in the instantaneous display state or to changes in the predetermined course of taking different display states.

There are numerous applications for banknotes 1,1 'in which, for example, by means of the device 10 after the FIG. 4 , by writing data into the memory of the chip 4, a reproduction state of the display 5, 5 'can be changed.

Thus, the display can be used to provide information about the validity of the bill. For example, if the display of the bill flashes when supplied with energy from the outside, this should mean that the bill is currently valid. If the display does not light up, the banknote is invalid. The occupancy can also be reversed. In this case, changing the display state is therefore only an activation or deactivation of the display. Since the reproduced information is thus selected from only two states, it is preferable to select as display a binary display which is only two different ones States can take. For this purpose, for example, a modified variant of the banknote 1 'of FIG. 3 can be used, in which the punctiform LED 5 'can be selectively switched on and off by the coupling of control signals by means of a then necessary receiving antenna of the chip 4.

This application also makes sense when banknotes are temporarily disabled, i. to be invalidated. For example, when banknotes are moved from one location to another, e.g. deactivated by the issuing central bank to a commercial bank, so banknotes stolen in such a transport in a robbery can be easily identified. It is also conceivable that banknotes are activated only immediately before the issue to a customer in a bank or out of an ATM. Moreover, e.g. in the case of extortionist money, into the memories of the banknote chips such data are written which results in a time-delayed blocking, i. Deactivation of the display 5 'lead, so that only after a time delay after the transfer of money to a blackmailer this is marked as invalid and can be detected.

Among other things, in the above-mentioned cases, it is particularly important that the display of the current validity of the banknotes can be changed only by authorized persons. This can be achieved by storing the data in the chip 4 encrypted and / or protected by a password and changed only with knowledge of the password or the encryption algorithm or just me specifically on the description of the associated banknote chips devices 10 associated chip data can be. For this purpose, the memory may include, for example, an authentication system, the data on different access permissions for reading and / or changing the data content of the memory. Furthermore, in the case of changes in the data content of the memory, which relate to changes in the reproduction state of the reproduction device, identification data can be stored in the memory, indicating from whom and / or with which device and / or when and / or where the associated data was entered into the memory in order to be able to clearly track and control the changes made later by reading out the memory contents. In the case of activating or deactivating banknotes, the writing devices will be present exclusively at the banks responsible for this.

Another application for banknotes 1,1 'with display may be that the display is used as an information or advertising space on which information is presented. Thus, the information content reproduced by the display may relate to information about a purpose of use of the respective banknote. In this case, the use of the bill is not completely free, but a particular use, such as the use of the bill. the purchase in certain transactions or of certain goods is considered preferred or limited or excluded. This display of the purpose can be mandatory or only as a recommendation.

In this connection, it is possible for a shop to display its logo by writing corresponding data in the memory of the chip 4 in the display 5, 5 'and to accept the so marked banknotes 1 as a discount voucher. For a banknote 1 with a denomination of € 100, the customer would, for example, receive goods worth € 110. Furthermore, it can also be indicated that the banknotes are only exchangeable for certain goods or groups of goods, so that in banknotes 1, the example issued by the parents to their children as pocket money, the display shows 5 icons indicating that no money such as alcohol or cigarettes may be purchased with the money in question. It can also be provided that set thereon test devices in a checkout of a department store, for example, read the display 5 memory contents of the banknote chips 4 and refuse the acceptance of such banknotes for the payment of excluded by the display 5 goods.

If e.g. If the goods purchased in the department store are lower in value than the denomination of the banknotes 1, the indication of use can preferably be accepted for the change which is issued to the customer. The paid-in banknote 1 is therefore automatically recognized during the deposit process into the cash register and the change is marked in accordance with the indicated intended use of the deposited banknote by means of a contactless coupling with the chip of the change banknotes via an integrated or external writing device in the cash register.

It should be noted that a display according to the invention may also be integrated in coins, so that in the aforementioned case e.g. the purpose of use can also be accepted for the coins of change.

In addition to the above-described embodiments of banknotes with an optical display, a value document according to the invention may also comprise an integrated acoustic reproduction device. FIG. 5 shows an embodiment of such a banknote 1 "with an electroacoustic sound transmitter 17, which is integrated in the banknote paper 3. In addition, a piezoelectric transducer 18 is firmly inserted in the banknote paper 3. The transducer 18 serves to generate by compressing the transducer 18 electrical energy which is transmitted via a signal line 19 to the sound transmitter 17 and this excited to emit acoustic sound waves audible by humans.

The compression of the transducer 18 can be accomplished either by squeezing the fingers or e.g. by tapping banknote 1 "on a firm base such as a table.

An alternative embodiment of such a banknote 1 "with sound transmitter shows the FIG. 6 , This is different from the one after FIG. 5 in that no piezoelectric transducer is present as the energy source, but that the energy for operating the sound transmitter 17 is transmitted contactlessly through an external alternating field to a security thread 2 acting as an open dipole antenna. The security thread 2 is analogous to the banknote 1 after the Figures 1 and 2 coupled to a chip 4, via which the receiving energy is supplied to the sound transmitter 17 via the signal line 20.

Furthermore, the energy supply could also be effected by means of a photocell, which is integrated in the paper, as for example in the banknote FIGS. 1 and 2 the case is. To prevent in this case that the banknote constantly emits acoustic signals when illuminated, the activation of the sound transmitter 17 can be triggered for example by means of a piezoelectric transducer 18, which corresponds to the example of FIG. 5 is integrated in the paper 3. Here, after compression of the transducer 18, the energy provided by the photocell is supplied to the sound transmitter 17, so that this then for a limited period of time, for example, the duration corresponds to the compression of the transducer 18, emits acoustic signals.

It should be emphasized that the aforementioned embodiments, which relate to the temporal changes of the display state of the display 5, 5 ', can also be used in a banknote 1 "with sound transmitter 17 in an analogous manner.

Thus, not only the playback state can be changed by changing, for example, the brightness of the display, but accordingly in the presence of a sound transmitter whose volume. Further, the temporal change of the reproduced information content may be e.g. mean that the sound transmitter plays different playback frequencies or frequency sequences.

An embodiment which is also preferred in the case of the optical display 5, 5 ', but which is particularly advantageous for the variant with sound transmitter 17, is intended to facilitate the optical or acoustic differentiation of banknotes 1, 1', 1 "of different denominations by making the display states This can be achieved by emitting different word or sound sequences, for example also analogously to the Morse alphabet, by combinations of short beeps or else by different sound frequencies or optically displayed patterns 16a, 16b for each nominal value the emission of acoustic signals in this case has the advantage that such banknotes can be distinguished safely and easily by blind people.

FIG. 7 shows another bank note processing device 30. The device 30 can be a banknote deposit device 30 for processing banknotes, such as the banknotes 1-1 "after the FIGS. 1, 2, 3 . 5 or 6. By way of example, it is shown that banknotes 1 "are input into an input compartment 31, withdrawn individually by means of a singulator unit 32 and checked by a sensor device 33. Thereafter, they are activated by a control unit 36, which is connected inter alia to the sensor device 33 and a downstream diverter 37, the accepted banknotes 1 "deflected into a cassette 34 and stored or the unaccepted banknotes 1" in an output tray 35 to the depositor reissued.

The sensor device 33 is characterized in that it can measure the optical or acoustic signals emanating from the reproducing device according to the invention of the banknotes. These measurement signals are then compared with predetermined reference values corresponding to genuine banknotes to determine if the banknote being tested is genuine. The authenticity is preferred to be confirmed only if the examination of further machine-readable security features, which the banknotes usually have, is also positive.

It can be provided that the banknotes 1-1 "for the reproduction of acoustic and / or optical signals by an activation unit associated with the sensor device 33, for example by optical, mechanical, electrical and / or magnetic coupling, is stimulated.In the case of an acoustic reproduction For example, this can be done by irradiating a photocell, pressing a pressure-sensitive element 18 and / or coupling by means of a dipole antenna 2 as described in FIGS FIGS. 5 and 6 respectively.

Furthermore, in the case of acoustic reproduction devices, the sensor device 33 can comprise a sound detector which detects the acoustic signals emanating from the bank note 1. The sound detector with the associated transport system is preferably used for transporting the banknote 1 "to be measured in this region, e.g. be mounted silenced in a housing to reduce in the measurement disturbing background noise by other machine components.

To determine the authenticity, the control unit 36 in a simple embodiment will only check the presence or absence of acoustic signals of a predetermined minimum intensity. Preferably, the test will here or alternatively only detect one or more specific frequencies and / or frequency ranges or extract them from the measured values by means of a frequency analysis, optionally taking into account background noise which normally occurs. In addition or alternatively, the temporal behavior of the measured signals can also be evaluated. For example, in the case where the reproducing device of the banknote 1-1 "outputs temporally pulsed signals, at least when the pulse intervals are in orders of magnitude still allowing testing at a desired speed, it is determined whether the interval of the individual signals is correct Since banknote processing devices usually require high throughput rates, it is advantageous for the banknotes 1-1 "to be excited by an associated activation unit into pulsed signals with a high-frequency signal sequence, ie pulses with short time intervals. The signal repetition frequency will preferably be on the order of 10 Hz or higher.

If the signals of the display devices are e.g. Depending on the denomination, the reference values with which the measured signals are compared are likewise specified corresponding to the particular denomination. The choice of suitable reference values is preferably effected by the fact that in the sensor device 36, the potential denomination of the banknote to be checked is previously concluded on the basis of other measured values. Alternatively, the measurements of the signals of the display device may be used to obtain an indication of the possible denomination of the bill to be checked. In order to definitively determine the authenticity of the banknotes, it is preferably determined here whether the checks actually also all point to the same denomination of other security features.

The abovementioned embodiments also apply in principle to the detection of signals from optical reproduction devices. In a simple case, for example, only any photosensitive element may be present as a sensor device 33, which, for example, with variable signals at blinking displays 5 'as after FIG. 3 checks whether the flashing signals emanating from the banknote 1 'with the appropriate signal spacing and / or with suitable frequencies. Optionally, the sensor device 33 may also comprise an area sensor, such as a CCD array, or a line sensor read out in cycles, in order to record a two-dimensional image of the display device and to compare it with the expected display of a genuine banknote.

Of course, the aforementioned embodiments can also be used in other banknote processing machines, such as sorting and / or counting devices, in which the authenticity of sheet-shaped value documents is to be determined.

The present invention thus provides a man-made and / or machine authenticated verifiable authenticity feature that can not be reproduced copying technically deceptive.

Claims (14)

1. A sheet-shaped value document, such as a bank note (1, 1', 1"), having an electro-optical and/or acoustic display device (5, 5', 17) integrated in the value document, which can display an information content optically or acoustically and which comprises an interface for the signal drive of the display device, in particular by optical and/or electronic means,
   wherein the interface is connected via a signal line (6, 20) to a control device (4, 10) integrated in the value document, which can change a display state of the display device and comprises an externally writable data memory (4) to permit the display state of the display device to be changed by changing a data content of the memory, wherein at least a part of the data content of the memory (4) is stored encrypted and/or secured by a password.
2. The value document according to claim 1, characterized in that the display device comprises a self-luminous optical display radiating in the visible, infrared and/or UV spectral range, and/or a non-self-luminous optical display.
3. The value document according to claim 1 or 2, characterized in that the display device comprises a display consisting of electronic paper and/or an LCD (5, 5') and/or an LED (17).
4. The value document according to any of claims 1 to 3, characterized in that the display device (17) comprises an electroacoustic audio transmitter (17) or a reciprocal piezoelectric audio transmitter or a magnetostrictive audio transmitter.
5. The value document according to any of the previous claims, characterized in that the control device (4, 10) can drive the display device, e.g. switch it on and off, to change the display state by the information content being displayed only temporarily.
6. The value document according to any of the previous claims, characterized in that the control device (4, 10) can drive the display device to change the display state by the control device temporally changing the displayed information content.
7. The value document according to any of the previous claims, characterized in that the display device (5, 5') is so designed that it can display several information contents at the same time and/or the control device (4, 10) is so designed that it can switch the display device (5, 5', 17) between more than two different display states.
8. The value document according to any of the previous claims, characterized in that the display device (5, 5', 17) assumes in each case one of two or more different display states in a predefined temporal alternation.
9. The value document according to any of the previous claims, characterized in that the memory (4) comprises an authentication system containing data about different access authorizations for reading and/or changing at least a part of the data content of the memory.
10. The value document according to any of the previous claims, characterized in that upon changes of the data content of the memory (4) that relate to changes of the display state of the display device (5, 5', 17), identification data are stored in the memory which state by whom and/or with what apparatus (10) and/or when and/or where the associated data were inputted to the memory (4).
11. The value document according to any of the previous claims, characterized in that the optical display device (5, 5') displays text and/or symbols, such as pictographs, as the information content, and/or the acoustic display device (17) emits sound signals which are specific to a nominal value of the value document.
12. The value document according to any of the previous claims, characterized in that the display device (5') displays information on the instantaneous validity of the value document as the information content.
13. The value document according to any of the previous claims, characterized in that the display device (5) displays a purpose of use for the value document as the information content.
14. Use of a sheet-shaped value document according to any of the previous claims for displaying information on the instantaneous validity of the value document and/or a purpose of use for the value document, by means of the display device.

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