Registers – Records – Conductive
Patent
1987-06-23
1989-10-10
Pitts, Harold I.
Registers
Records
Conductive
235468, G06K 1906
Patent
active
048734276
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a card or pass formed of plastic material and incorporating an integrated memory circuit and an univocal optical code for identification of the card. At present such supports are for instance widely used for credit cards, automatic cash-point cards and identification passes.
Such a memory support is useful in all of those cases where high data safety and protection against fraud resulting from unlawful manipulation are required. In particular, it is utilized for electronic memory credit cards where data safety and small dimensions of the electronic device are fundamental to the reliability of the product.
BRIEF DESCRIPTION OF THE PRIOR ART
The data protection devices presently available are obtained by providing in the card a further device (normally a suitably programmed single chip microprocessor) which works as a filter between the memory and the outside world. This device or microprocessor can also be on the same silicon chip which houses the memory matrix. Such an arrangement entails a series of drawbacks. First of all, the microprocessor occupies a considerable area of the silicon chip, with the consequence of increasing considerably the cost of the device. Secondly, the microprocessor requires a series of interfacing signals towards the external world (clock, reset...) which necessarily complicate the connection with the writing/reading devices. Thirdly, the program contained on the microprocessor can be read by using suitable techniques, thus making the system less safe.
The presently available cards or passes, of the type to which the present invention applies, foresee more than four external electric contacts, on two rows, for connection with the internal circuit. Since the electric and mechanical reliability of such devices is in inverse ratio to the number of connecting contacts, the assembly is of poor reliability during usage. Moreover, the writing and reading devices to be used with this support are complex and expensive owing to the intrinsical difficulty of carrying out contact means which maintain a good alignment in the course of time.
SUMMARY OF THE INVENTION
One object of this invention is therefore to carry out a credit card or similar device which is extremely strong, that is as flexible and capable of withstanding wear and tear as much as possible, which allows for protection of the data contained in an electronic memory, not including programmed logic, against access and/or alteration attempts from unauthorized persons, and to allow the reading and/or writing with devices less complicated than the existing ones.
According to the invention, a support comprising an integrated memory circuit of EEPROM technology is provided. This is connected with the outside only through four contacts and contains voltage conversion circuits able to generate internally, starting from a single voltage (for instance 5 volts), the one necessary to the programming of the memory cells, with the consequence that the integrated circuit works with a single feeding voltage. Through one of the contacts an input signal (for instance at 5 volts in continuous current .+-.5%) is transmitted and through another contact a connection with the input outgoing line is foreseen. A logical type signal passes through a further contact and acts as clock signal for data and instructions and an open drain bi-directional line (SDA) passes through a fourth contact which acts as support for data and instructions. Preferably, the signals have the logical "zero" included between -1 V and 0.8 V and the logical "one" included between 2 V and VCC+0.5 V.
An improvement provides for the integrated memory circuit to have an asynchronous serial interface on two wires and contains the necessary circuits for handling a feeding protocol with an external writing and/or reading device for handling the writing timing, for the random access to any memory byte and for any other operation which might be required.
A further improvement provides for the integrated memory circuit to
REFERENCES:
patent: 4004133 (1977-01-01), Hannan
Pentasystem S.p.A.
Pitts Harold I.
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