EMBEDDED SMART CARD DISPLAYThe present invention relates to a smart card.
Today, smart card applications span various sectors of everyone's life and will penetrate more and more fields within the next few years.
Cashless payment, health care, social security, access control, authentication and retail loyalty bonus are only a few examples of applications that will expand in terms of quantity and range. The move from individual cards for each application to a single card holding multiple applications for different purposes has only just begun. Simple magnetic stripe cards are increasingly replaced by microprocessor based 'smart' cards that offer sophisticated computational abilities.
One of the most irksome problems facing the users of smart cards is not knowing the state of the smart card, for example, how much money or credits they have in their electronic "purse", unless they can access a reader device (e.g. an ATM or a key-fob reader). This contrasts poorly with a normal wallet where one just opens the wallet and counts the cash.
Accordingly, the present invention provides a smart card including a processor adapted to communicate with a smart card reader and memory whose state can be updated by said processor when the smart card is placed in said reader characterised in that the smart card includes an integral non-volatile display connected to said processor, said display contents being updatable according to the state of said memory when power is applied to said display.
The present invention provides a smart card including a display allowing, for example, the contents of an electronic purse (or some other item of information) to be displayed at all times.
The main advantage of the invention is that the user of the smart card can always be aware of its contents. Also, the card display offers several advantages over even the smallest current display devices such as a key-fob reader: unlike a key-fob reader no batteries are required (or can therefore run down), space is not required in a pocket or handbag for a relatively bulky device, and the display is not perceived as costing the user extra, which might be the case with reader devices.
An embodiment of the invention will now be described with reference to the accompanying drawing which is a diagram of the key elements of a smart card with a display according to the present invention.
The smart card 10 comprises a processor 12 which includes memory 13 which is at least partially electrically erasable non-volatile memory for storing both smart card program code and data. The processor 12 can connect to a smart card reader in any number of ways. Traditional cards include a set of contacts (not shown) on the surface of the card located in register with the processor 12. The contacts connect with complementary contacts in a smart card reader so that the reader can supply power and thence communicate with the processor 12 to execute transactions on the smart card. Variations such as radio frequency (RF) transmitter cards employ a contactless wireless connection with the smart card reader. The invention is not limited to either form of power supply and communication and could for example encompass infra red or some other form of communication between the smart card and smart card reader. In any case, smart cards are characterised in that they usually, although not necessarily, do not include an on-board power supply. For this reason, it was not thought necessary or possible to include a display on such cards, as it could not be powered once the smart card is removed from its reader.
The smart card of the present invention comprises a non-volatile display 16 connected via a bus 15 to a display driver 14 which in turn is connected via another bus 11 to the processor 12. The key requirements of the display 16 are that:the display 16 does not require power in order to maintain the display contents because smart cards, in general, have no power supplies on board;the necessary display driving circuitry 14 can either be incorporated into the smart card processor chip 12 thus obviating the need for a discrete bus 11; or the display driver 14 could be embedded elsewhere in the smart card and connected to the processor chip by address and data lines 11 as shown in the figure;the display 16 is thin enough and robust enough to be mounted in the smart card; and the display 16 and associated driver circuitry 14 is cheap enough to be worth mounting in a smart card.
Ferroelectric liquid crystal molecules are endowed with a positive or negative polarity in their natural state, even without the application of an electric field. In other words, ferroelectric liquid crystal displays (LCDs) utilize intrinsic polarization. Ferroelectric LCDs are, however, being developed primarily for relatively large screen moving picture applications because they offer the following unique characteristics which differ from conventional LCDs:ferroelectric display images are not lost when the power is cut; the image remains intact. Since the arrangement the liquid crystal molecules had when voltage was last applied is retained, the number of scanning lines in a display can be increased without sacrificing contrast quality;very high-speed displays are possible. Speeds more than 3,000 times faster than twisted nematic (TN) LCDs;the contrast in a ferroelectric LCD does not change depending on the viewing angle and so viewing angle limitations are reduced. Thus, high resolution, large-scale LCDs are possible; andferroelectric LCDs do not require expensive switching elements like active matrix drive systems (as thin film transistor (TFT) LCDs do), making large-scale high-resolution displays with large information capacity possible using simple passive matrix addressing.
A Ferroelectric LCD meets the requirements of the above invention because as it does not require power to maintain the current contents of display, it only requires power to change the contents of the display. An example of a ferroelectric LCD manufacturer producing a film suitable to be adapted for use in the present invention is Displaytech Inc., USA.
Thus, a smart card according to an embodiment of the invention incorporating a ferroelectric LCD can always show its current state and each time it is put in a device that can change its state (e.g. an ATM or a smart card reader), power is available for the processor to update the display contents after any transactions are completed, thereby ensuring an up to date display.
The display 16 is preferably a simple seven-segment numeric display on the basis that this would be cheapest to manufacture and would only require the simplest display controller. However, the invention does not exclude a dot-matrix (or hybrid dot-matrix / numeric) display, as this would provide greater flexibility, particularly in identifying the currency in use or which application's contents are being displayed on a multi-application smart card. A dot-matrix display would also open up the possibility of displaying messages (e.g. "CARD STOLEN") rather than simply credit/cash contents.
Clearly, such a display could also be used by other applications on the smart card (e.g. for a credit card application to show the amount of available credit). Also, if a dot-matrix or hybrid display was used, a smart card could (at the user's discretion) display text and symbols (e.g. a currency symbol could be displayed to show the electronic purse contents in local currency rather than home currency).