WO2002035465A1

WO2002035465A1 - Plastic card with lep display

Info

Publication number: WO2002035465A1
Application number: PCT/US2001/032600
Authority: WO
Inventors: George Blossom
Original assignee: First Usa Bank, N.A.
Priority date: 2000-10-23
Filing date: 2001-10-23
Publication date: 2002-05-02
Also published as: AU2002215385A1

Abstract

A plastic card (150) comprising a thin, flexible, LEP display (128) that does not fracture under normal card use, handling and storage conditions and emits light having a brightness of from about 50 to about 500 cd/m2 at sufficiently low power requirements. The LEP display (128) comprises a light emitting polymeric material operatively connected to a power source (152) via metal electrodes (224, 225).

Description

PLASTIC CARD WITH LEP DISPLAY

FIELD OF THE INVENTION

The present invention generally relates to plastic cards such as credit cards, debit cards, transfer funds cards, smart cards, identity and security cards. More particularly, the present invention relates to an improved plastic card having a light emitting polymer (LEP) display.

BACKGROUND OF THE INVENTION

Conjugated polymers, i.e., polymers having double or triple bonds in a molecule that are separated by one single bond, are known to emit light when subject to an applied electric field. This phenomenon is known as electroluminescence (EL). Conjugated polymers possess a delocalised π-electron system along the polymer backbone which confers semiconducting properties to the polymer and gives it the ability to support positive (hole) and negative (electron) charge carriers with high mobilities along the polymer chain. The combination of these charge carriers in neutral species results in the emission of light.

The use of conjugated polymers in making light emitting devices is also known. For example, U.S. Patent No. 6,004,681 to Epstein, U.S. Patent No. 5,672,678 to Holmes et al., U.S. Patent No. 5,807,627 to Friend et al., U.S. Patent No. 5,399,502 to Friend et al., and U.S. Patent No. 5,653,914 to Holmes et al. describe light emitting devices that employ conjugated polymers and are incorporated herein by reference for all purposes.

Plastic cards are widely used for payments, cash advances, and other transactions, security and identification purposes. They can be generally classified into magnetic cards and smart cards. Magnetic cards, such as for example a credit card, employ a magnetic strip or tape for storing data that identify the card owner, the account number, security code or other information. Smart cards contain a semiconductor chip with some electronics and a memory for storing information. Smart cards are used to store personal information, ranging from medical information to financial data, as well as to store monetary value. The large amount of information, or data, stored on a smart card is not generally accessible or capable of editing or use without the intervention of a smart card device that is capable of being interfaced with the smart card. Many different smart cards are presently in use, including those that operate at a variety of different voltages, those that can be accessed by electrical contacts, contactless cards, etc.

A conventional smart card includes a processor coupled to an electrically erasable programmable read-only memory (EEPROM), read-only memory (ROM) and random access memory (RAM). These components may be fabricated onto a single integrated chip comprising a microprocessing/controller unit (MPU). The processor executes instructions stored on ROM and temporarily stores data on RAM whereas the EEPROM is a non-volatile memory used for storing data identifying the uniqueness of smart card. A smart card also includes an input/output (I O) signal interface for transferring various I/O signals between the smart card and an external system. The I/O interface may take the form of a contact with the external system, or a peripheral thereof, for proper transfer of signals. Alternatively, the I O interface may take the form of a radio frequency (RF) interface for allowing communication between the smart card and the external system via the transmission and reception of RF signals. The external system may take the form, for example, of a card reader, a merchant's point of sale system, or an automated teller machine.

Typically, power is supplied to the smart card from the external system when the system communicates with the smart card. This may be accomplished through the I/O interface. However, this means that a smart card is only powered and its data is accessible only when the smart card is connected to the external system.

One of the widespread uses of smart card technology is as a stored-value card, which contains monetary value in the microchip embedded in the card. For example, each time a consumer uses a chip card in a vending machine, the amount of the purchase is deducted from the cash balance stored in the microchip on the chip card. One application for such stored-value chip cards is eliminating the need for people to carry around small coins or bills and speed up the time it takes to consummate small cash transactions. However, most chip cards do not offer built-in displays for viewing the cash balance remaining on the chip card. This reduces the convenience and ease of use of chip cards. Some have suggested including a display for allowing the card owner to view the stored information as well as means such as a keypad for editing information contained in the cards. For example, U.S. Patent No. 4,954,985 to Yamazaki describes a smart card with a ferroelectric, liquid crystal memory region and a ferroelectric, liquid crystal display region. U.S. Patent No. 5,777,903 to Poisenka, et al. describes a smart card having a microprocessing unit (MPU) for executing instructions stored in memory, a liquid crystal display (LCD), coupled to the MPU for displaying information, a keypad, coupled to the MPU and to the display for entering data by the user, an interface for transferring signals between the smart card and the external system when the smart card is coupled to the external system, and photovoltaic cells for providing power to the smart when the smart card is exposed to light.

One problem associated with existing displays for plastic cards like LCDs is that they are generally less flexible than the remainder of the plastic card. Thus, to keep them from fracturing under normal handling conditions the displays tend to be small, thick, and/or placed at areas of the plastic cards that are subjected to less flexing. Some have suggested larger LCDs formed from a plurality of individual smaller LCD elements which are mounted to the core segment of the plastic card with separation between them to allow for flexibility.

U.S. Patent 6,019,284 to Freeman et al. describes a smart card with an LCD display, comprising a thin, ferroelectric LCD film. These LCDs are based on smectic liquid crystals typically of the smectic C phase with chiral behavior. When formed in a thin layer the ferroelectric material has a net polarization that is perpendicular to the viewing surface. The electrodes apply a field that rotates polarization between an "on" and an "off state. Ferroelectric LCDs are typically sensitive to shock or bending, making them unsuitable for use in a plastic card that can be bent (e.g., when stored in a wallet). Other problems exist.

SUMMARY OF THE INVENTION

The present invention overcomes these and other problems associated with plastic cards having conventional LCDs. The present invention in one regard provides an improved plastic card having a thin, flexible, LEP display that does not fracture under normal card use, handling and storage conditions, e.g., storage in a pocket, wallet, or purse. The LEP display achieves at least similar brightness as conventional LCDs, preferably at sufficiently low voltage and power requirements to enable powering the LEP display with a miniature built-in power source, such as solar cells, and lithium based batteries. Preferably, the LEP display exhibits brightness of from about 50 to about 500, and more preferably from about 200 to about 400 cd/m² . The LEP of the present invention may be powered by an external power source when the plastic card is connected to an external system, or in the alternative the plastic card may be provided with a built-in power source that provides sufficient power to the LEP display to achieve the desired brightness level. Preferably, the operating voltage of the LEP display should be less than about 30 N, more preferably from about 5 to about 25 N and most preferably from about 8-15 N. The LEP may be controlled by logic devices that are part of the card, external to the card or both. The LEP display may comprise a light emitting polymeric material operatively connected to a power source via metal electrodes. Suitable light emitting polymeric materials include conjugated polymers such as poly (p-phenylene vinylene) (PPV), PPN derivatives, pyridine containing polymers and copolymers such as poly (p-pyridine) (PPy), poly (p-pyridyl vinylene) (PPyN), copolymers of PPyN and PPN derivatives (PPyVP(R)₂V) with various functional side groups R=Cι₂H₂₅, OC₁₆H₃₃, COOCι₂H₂₅, strapped copolymer, and other conjugated polymers and copolymers.

According to one embodiment of the invention a smart card may be provided comprising: a controller unit for controlling an operation of the smart card; an LEP display, coupled to the controller unit for displaying information; an input device, coupled to the controller unit and to the display, for entering data by the user; an interface for transferring signals between the smart card and an external system when the smart card is coupled to the external system, wherein power may be provided to the smart card from the external system through the signal interface; a power source for providing power to the smart card when the smart card is not connected to the external system; and a power interface for selectively powering the smart card with either power from said power source or power from the external system via the signal interface. In another embodiment the LEP display may comprise a semiconductor layer in the form of a thin dense polymer film comprising at least one conjugated polymer, a first electrode in contact with a first surface of the semiconductor layer and a second electrode in contact with a second surface of the semiconductor layer. The polymer film should have a sufficiently low concentration of extrinsic charge carriers so that on applying an electric potential between the first and second electrodes in a manner that renders the second electrode positive relative to the first contact layer charge carriers are injected into the semiconductor layer and light is emitted from the semiconductor layer.

In yet another embodiment, the LEP display may comprise an electron transporting layer in contact with an electron blocking polymer, the electron blocking polymer incorporating a network electrode polymer. The LEP display is connected to a source of electrical current via electrodes so as to supply the electron transporting polymer with a flow of electrons, and to cause an electroluminescent emission from the heterojunction between the electron transporting polymer and the electron blocking polymer.

The electron transporting polymer may be any conductive polymeric material of appropriate conductive and electron affinity characteristics to allow it to act as the electron transporting polymer in a light emitting device. Likewise, the electron blocking polymer may be any polymeric material of appropriate electron blocking-polymer characteristics to allow it act as the electron blocking polymer in a light emitting device.

The network electrode polymer may be any polymeric material that forms an electrically conducting network polymeric structure within the electron blocking polymer. According to another aspect of the present invention an advantageous method for making a plastic card with an LEP display is provided.

Other features and advantages of the invention will become apparent from the description of preferred embodiments in conjunction with the following figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a block diagram of the internal structure of a plastic card having an LEP display and interface keypad according to an embodiment of the present invention.

Figure 2A is a front view of the plastic card of Figure 1.

Figure 2B is a back view of the plastic card of Figure 1. Figure 2C is a cross-section of the plastic card of Figure 1.

Figure 3 is a schematic of a bilayer LEP display according to an embodiment of the invention . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to Figure 1, a block diagram of components of a plastic card 150 according to an embodiment of the invention is provided. The plastic card 150 may be a smart card that includes an input device 126 such as a keypad, and an LEP display 128 both of which are coupled to a controller or micro-processing unit (MPU) 118. Smart card 150 has an advantage of allowing the individual user of smart card 150 to conveniently access data stored within MPU 118 or external system 124 via the input device 126 and contactless interface 156. Information such as account balance and account status can be displayed in the LEP display 128. For example, the user may enter input data to smart card 150 via input device 126, and data returned from smart card 150 may be viewed on the LEP display 128.

Smart card 150 also includes contact interface 154 and/or contactless interface 156 and signal VO interface 162 for independently or selectively providing communication between smart card 150 and external system 124 by either signals coming into contact with smart 150, via contact interface 154, or by wireless signals, for capacitive or inductive coupled signals, being transmitted or received by smart card 150 via contactless interface 156. Information received from external system 124 can be displayed in LEP display 128. Also, power interface 158 provides power to MPU 118, input device 126 and display 128 via power line 160 by selectively providing power from power source 152 or from external system 124 via contact interface 154 or contactless interface 156.

Smart card 150 additionally includes a built-in power source 152 for providing power to the electronics and to the display 128 within smart card 150. The built-in power source 152 may be any of many different conventional power sources and may be replaceable and/or rechargeable. The plastic card may further include a mechanism to conserve power such as a conventional kickstart circuit (not shown). The plastic card may also include multi-media features (not shown) powered by the built-in power source 152. For example, the power source may power a speaker, a microphone, a video camera device, a biometric device or cause the display element to produce a series of images (e.g. a video clip) on the display 128. The power source 152 may also power communication elements of a contactless card. Preferably the power source 152 may comprise photovoltaic cells and more preferably, the photovoltaic cells 152 may take the form of solar cells. The power source 152 should preferably be flexible and relatively light weight and also provide sufficient power at a voltage determined by the operating voltage of the LEP display. Solar cells provide power to the smart card when it is exposed to light. This eliminates the need for a battery as well as the need for an on/off switch. However, since the light source may not be available when the card is inserted into, for example, an external system card reader, power may also be supplied via the card reader's contact or the card reader's supplied RF field for information exchanges. Accordingly, power to the smart card 150 may also be provided from an external system that communicates with the smart card 150 either through contact interface 154 or contactless interface 156. For example, a contactless power interface may include a combination of an inductive element with a storage capacitive device.

Turning to Figs. 2A, 2B, and 2C, there is shown a smart card having a transparent protective top layer 212 made from a transparent plastic resin such as PVC. The smart card also has a substrate 214 which can be transparent, opaque or translucent 214, and may be made from a plastic resin such as PNC. The top layer and substrate (body) may be molded or machined into the necessary shape to accommodate the internal components of the card. Indicia may be printed on the top layer (e.g., on the interior surface), and a hologram 232 may be installed beneath the top layer. A conventional magnetic strip 234 and signature panel (not shown) can also be provided on the bottom of the card (Fig. 2B).

An integrated circuit 216 may be mounted beneath a printed circuit board 218, which fits within a cutout in the card body. Contacts 220 may cover an entire surface of the printed circuit board 218 and be exposed to the outside of the card through the cutout, to provide electrical connection to the card. Alternatively, a wireless communication element may also be provided within the card. The size of the printed circuit board 221 is exaggerated in the cross sectional view of Figure 2C. Preferably, the printed circuit board 221 has the same lateral extent as the connector contacts 220, which may cover one surface of the board. A LEP display 222 may be provided on the top surface of the card. The LEP display 222 may comprise a light emitting polymeric film 226 placed between two metal electrodes 224 and 225. One method for making the LEP display may include depositing the electrodes 224 and 225 on the interior surfaces of the top protective layer 212 and substrate layer 214, respectively. The light emitting polymeric film 226 may be attached either beneath the top protective layer or on top of the substrate layer 214 prior to laminating the top protective layer 212 to the substrate layer 214, for example via the application of heat and pressure. The polymeric film 226 may be attached using any of conventional methods, such as for example using a thin adhesive layer. The electrodes 224 and 225 may be configured in any conventional pattern such as, for example, a dot matrix pattern, or a segmented display pattern.

In one embodiment, the LEP film may comprise at least one conjugated polymer having a sufficiently low concentration of extrinsic charge carriers so that on applying an electric potential between electrodes 224 and 225 in a manner that renders electrode 224 positive relative to electrode 225, charge carriers are injected into the LEP film and light is emitted from LEP film. Examples of conjugated polymers that can be used include poly (p-phenylene vinylene) (PPN), PPN derivatives, pyridine containing polymers and copolymers such as poly (p-pyridine) (PPy), poly (p-pyridyl vinylene) (PPyN), copolymers of PPyN and PPN derivatives (PPyNP(R) N) with various functional side groups OC₁₆H₃₃, COOCι₂H₂₅, strapped copolymer, and other conjugated polymers and copolymers. Conjugated polymers are those having higher electron affinities are preferably because they allow the use of more stable metals as electrodes. Light emitting polymeric materials, their synthesis and advantageous structures for increasing their electroluminescence (EL) are described in for instance U.S. Patent No. 6,004,681 to Epstein, U.S. Patent No. 5,672,678 to Holmes et al., U.S. Patent No. 5,807,627 to Friend et al., U.S. Patent No. 5,399,502 to Friend et al., U.S. Patent No. 5,653,914 to Holmes et al., which are incorporated herein by reference for all purposes. Examples of metals that can be used as electrodes 224 and 225 include aluminum, gold, magnesium/silver alloy, and indium oxide. Electrode 224, i.e., the top electrode should preferably be transparent or semitransparent in order to allow light emission from the LEP film perpendicular to the plane of the top surface of the card. This can be achieved, for example, by keeping the thickness of the metal electrode layer less than about 30 mm. In one embodiment the conjugated polymer may be PPN, electrode 224 may be a thin layer of aluminum oxide or indium oxide, and electrode 225 may be a thin layer of aluminum or gold. In another embodiment, the conjugated polymer may be PPN, electrode 224 may be aluminum or an alloy of magnesium and silver and electrode 225 may be indium oxide. A conductor 228 with conductivity in the Z-axis only, such as a polymeric material, may provide conductive paths from the printed circuit board to electrode 224. Alternatively, the printed circuit board may be connected to both electrodes 224 and 225.

In a preferred embodiment the light emitting polymer film 226 may be a bilayer film as seen in Figure 3. According to the embodiment of Figure 3, the bilayer film 226 may comprise an electron transporting polymer film 226B in contact with an electron blocking polymer film 226A. Moreover, the electron blocking polymer film 226A may include a network electrode polymer (not shown). The LEP display may be connected to a source of electrical current via electrodes so as to supply the electron transporting polymer with a flow of electrons, and to cause an electroluminescent emission from the heterojunction between the electron transporting polymer and the electron blocking polymer. The electron transporting polymer may be any conductive polymeric material of appropriate conductive and electron affinity characteristics to allow it to act as the electron transporting polymer in a light emitting device. Examples of such polymers include pyridine-containing conjugated polymers and copolymers, and their derivatives. Likewise, the electron blocking polymer may be any polymeric material of appropriate electron blocking-polymer characteristics to allow it act as the electron blocking polymer in a light emitting device, such as those selected from the group consisting of poly(vinylcarbazoles) and their derivatives.

The network electrode polymer may be any polymeric material that forms an electrically conducting network polymeric structure within the electron blocking polymer. Examples include camphor sulfonic acid doped polyanilines. The network electrode polymers employed in the present invention may be produced through methods known in the art such as those used in the synthesis of extended π-systems and in the synthesis of ladder polymers. Further details of this bilayer structure and methods for making it are described for instance in U.S. Patent No. 6,004,681 to Epstein et al. which is incorporated herein by reference for all purposes. The bilayer structure can be made, for example, by spin coating at about 3000 rpma poly (9-vinyl carbazole) (PVK) layer 226A onto an ITO substrate from appropriate solutions. For example, the PVK may be spin coated from a solution in tetrahydrofuran (THF) having a concentration of about 10 mg/ml. An emitting layer may then be spin coated on top of the PVK layer from appropriate solutions. The conducting polyaniline network electrode may be formed by a spin-cast blend of camphor sulfonic acid doped polyaniline (PAN-CSA) and low molecular weight host polymer poly(methyl methacrylate) (PMMA) (for example from Aldrich Chemical Co.) in an appropriate ration in m-cresol. The host polymer PMMA may subsequently be washed away by xylenes. The PVK and emitting layers may be similarly coated as in the bilayer device. All solutions may be filtered using for example Gelman Acrodisc CR PTFE 1 μm filters. The top metal electrode may be deposited by vacuum evaporation at a pressure below 10^"6 torr. To prevent damage to the polymers, the substrate can be mounted on a cold-water cooled surface during evaporation.

A source of electrical current supplies the electron transporting polymer with a flow of electrons, so as to cause light emission from the heterojunctiion between the electron transporting polymer and the electron blocking polymer. The electrodes 224 and 225 may preferably be made from transparent indium tin oxide (ITO) or other substantially clear conductive materials.

The foregoing embodiments have been presented for the purpose of illustration and description only, and are not to be construed as limiting the scope of the invention in any way. The scope of the invention is to be determined from the claims appended hereto.

Claims

CLAIMSWe claim:

1. A card comprising: a flexible, LEP display that does not fracture under normal card use, handling and storage conditions, emits light having sufficient at sufficiently low power requirements, said LEP display comprising a light emitting polymeric material operatively connected to a power source via electrodes.

2. The card of claim 1, wherein said light has a brightness of from about 50 to about 500 cd/m².

3. The card of claim 1, wherein said power source comprises an external power source that provides sufficient power to light the LEP display to achieve a brightness of emits light having a brightness of from about 50 to about 500 cd/m at sufficiently low power requirements. .

4. The card of claim 1, wherein said power source comprises a built-in power source that provides sufficient power to light the LEP display to achieve a brightness of from about 50 to about 500 cd/m² at sufficiently low power requirements.

5. The card of claim 1, wherein the LEP display operates at a sufficiently low voltage and power requirements to allow powering the LEP display with a built-in power source.

6. The card of claim 1, wherein said light emitting polymeric material is selected from the group consisting of PPV, PPV derivatives, PPy, PPyV, copolymers of PPyV and PPV derivatives with functional side groups R=Cι₂H₂₅, OC₁₆H₃₃, COOCι₂H₂₅, strapped copolymer, and other conjugated polymers and copolymers.

7. A smart card, comprising: a controller unit for controlling an operation of the smart card; an LEP display, coupled to the controller unit for displaying information; an input device, coupled to the controller unit and to the display, for entering data by the user; an interface for transferring signals between the smart card and an external system when the smart card is coupled to the external system, wherein power may be provided to the smart card from the external system through the signal interface; a power source for providing power to the smart card when the smart card is not connected to the external system ; and a power interface for selectively powering the smart card with either power from said power source or power from the external system via the signal interface.

8. The smart card of claim 6, wherein said card comprises an LEP display sufficiently flexible as to not fracture under normal card use, handling and storage conditions, and emits light having a brightness of from about 50 to about 500 cd/m² at sufficiently low power requirements, said LEP display comprising a light emitting polymeric material operatively connected to a power source via metal electrodes.

9. The smart card of claim 7, wherein said power source comprise an external power source that provides sufficient power to the LEP display to achieve said brightness.

10. The smart card of claim 7, wherein said power source comprises a built-in power source that provides sufficient power to the LEP display to achieve said brightness.

11. The smart card of claim 7, wherein the LEP display operates at a voltage ranging from about 1 V to about 30 V.

12. The smart card of claim 7, wherein said light emitting polymeric material is selected from the group consisting of PPV, PPV derivatives, PPy, PPyV, copolymers of PPyV and PPV derivatives with functional side groups R=Cι₂H₂₅, OCι₆H ₃, COOCι₂H ₅, strapped copolymer, and other conjugated polymers and copolymers.

13. The smart card of claim 7, wherein the smart card comprises an LEP display comprising a semiconductor layer in the form of a thin dense polymer film comprising at least one conjugated polymer, a first electrode in contact with a first surface of the semiconductor layer and a second electrode in contact with a second surface of the semiconductor layer, the polymer film having a sufficiently low concentration of extrinsic charge carriers so that on applying an electric potential between the first and second electrodes in a manner that renders the second electrode positive relative to the first contact layer charge carriers are injected into the semiconductor layer and light is emitted from the semiconductor layer.

14. The smart card of claim 6, wherein the smart card comprises an LEP display comprising an electron transporting layer in contact with an electron blocking polymer, the electron blocking polymer incorporating a network electrode polymer, and wherein the LEP display is connected to said power source via electrodes so as to supply the electron transporting polymer with a flow of electrons, and to cause an electroluminescent emission from the heterojunction between the electron transporting polymer and the electron blocking polymer.

15. The smart card of claim 6, wherein said input device allows a cardholder to activate contactless communication between the card and an external system for interactively communicating with said external system via messages displayed in the LEP display.

16. A method for making a plastic card with an LEP display, comprising: providing a plastic substrate layer; providing a top protective layer; depositing a first metal electrode on a first surface of said plastic substrate layer; depositing a second metal electrode on a first surface of said top protective layer; adding an LEP film beneath said second electrode; and laminating the top protective layer to the substrate layer.

17. The method of claim 15, wherein said adding step comprises applying an adhesive layer between said LEP film and said second electrode of said top protective layer.