Registers – Records – Conductive
Reexamination Certificate
1999-02-17
2001-04-10
Lee, Michael G. (Department: 2876)
Registers
Records
Conductive
Reexamination Certificate
active
06213402
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a data carrier with a coil for communication, i.e., for the contactless reception of data and energy and the contactless transmission of data. The data carrier has a logic circuit for processing and storing the received, demodulated, and decoded data.
Currently, such data carriers are used primarily as so-called contactless smart cards (chip cards), or, if in addition to the contactless interface they are also provided with terminal contacts, as so-called combination cards or dual interface cards. However, their use is not restricted to the form and shape of a card, since they have also already been proposed in wristwatches and hang tags, for instance for ski lifts.
In ISO Standard 14443 for the contactless interface of such smart cards, two different kinds of modulation for the data, transmitted from a read/write station to a card, are listed. These are pure blanking of the data carrier, which is also known as on-off keying and has the working title ASK100%, and Amplitude Shift Keying (ASK) modulation with a modulation depth of 5% to 15%, with the working title ASK10%. The terms “ASK10%” and “10%-ASK-modulated signals” as used herein refers to a type of modulation as defined by ISO Standard 14443.
Different kinds of bit coding are associated with these types of modulation. For instance, with ASK100%, pulse position coding is employed. The type of modulation and bit coding of the data, sent from a smart card to a read-write station, may also be different.
ASK100% has the advantage of being easy to demodulate, since all that is required is a blanking gap detection circuit. However, during the blanking gap, the clock pulse is missing, and relatively major sidebands occur in the frequency spectrum.
ASK10%, by comparison, makes a continuous clockline possible and entails a substantially lower level of sidebands but is difficult to demodulate, because on the one hand the distance between the card and the read-write station can fluctuate greatly, the circuits on the side of the card have a severely fluctuating current consumption, and the circuitry options for the demodulator circuit are limited, since no sufficiently constant, adequately high voltage supply is available.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a data carrier for the contactless reception of data and energy, and a method of operating such a data carrier, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which allows both types of modulation to be received and furnishes unambiguous data.
With the foregoing and other objects in view there is provided, in accordance with the invention, a data carrier, in particular a smart card, comprising:
a coil for contactless data and energy reception and for contactless data transmission;
a logic circuit connected to the coil, the logic circuit processing received, demodulated and decoded data;
a first demodulator for demodulating 100%-ASK-modulated signals received by the data carrier;
a second demodulator connected to the first demodulator for demodulating ASK-modulated signals received by the data carrier having a modulation depth of less than 100%;
the second demodulator being triggered by the first demodulator such that, on receiving a 100%-ASK-modulated signal, the second demodulator is deactivated by the first demodulator.
In other words, the two demodulators can demodulate 100%-ASK- or 10%-ASK-modulated signals, respectively. When a 100%-ASK-modulated signal is received, that is, when the first blanking gap is received, the 10%-ASK demodulator is deactivated, since while it can receive 100%-ASK-modulated signals, nevertheless the ensuing decoding produces completely incorrect results. The data carrier according to the invention accordingly assures that unambiguous demodulation and decoding will always take place.
In accordance with an added feature of the invention, a status register is connected to the first and second demodulators via control lines. The status register indicates to the logic circuit which of the first and second demodulators is active at a given time. The status register is triggerable by the demodulators to indicate which demodulator is active. The status register can be polled by the logic circuit, for instance via a common bus.
In accordance with an additional feature of the invention, a voltage supply device is connected via a control line to the logic circuit. The voltage supply device is adjustable to an optimum depending on the type of modulation of the signal being received.
In accordance with another feature of the invention, the logic circuit has a reset input, and the first demodulator has an output connected to the status register for triggering the status register. A switch is connected between the output of the first demodulator and the reset input of the logic circuit. The switch is connected to and driven by the second demodulator.
The output of the 100%-ASK demodulator that indicates the reception of a blanking gap thus can be connected, after a 10%-ASK data bit is received, with the reset input of the logic circuit of the data carrier, so that the entire data carrier is reset, since the occurrence of a blanking gap in a 10%-ASK-modulated signal is an indication of an error or manipulation.
With the above and other objects in view there is also provided, in accordance with the invention, a method of operating the above-described data carrier. The method comprises deactivating the second demodulator with the first demodulator upon receiving a first blanking, and deactivating the first demodulator with the second demodulator no earlier than after receiving a first data bit. In other words, after the first data bit of a 10%-ASK-modulated signal, the 100%-ASK demodulator is deactivated. This provision assures an unambiguous functional state of the circuit.
In accordance with another feature of the invention, the second demodulator is deactivated by the first demodulator upon receiving a first blanking, and when a blanking occurs during a reception of an ASK-modulated signal with a modulation depth of less than 100%, the logic circuit is reset.
In accordance with a concomitant feature of the invention, a voltage supply device is adjusted to optimal operation with the logic circuit as a function of a state of the status register.
Since the power transmission when a 10%-ASK-modulated signal is received differs substantially from that when a 100%-ASK-modulated signal is received, it is advantageous to trigger the voltage supply device with the logic circuit as a function of the state of the status register. This attains an optimal adjustment. As an alternative, the triggering can also be done by the demodulators.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a data carrier for contactless reception of data and energy, and method for operating such a data carrier, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
REFERENCES:
patent: 4605844 (1986-08-01), Haggan
patent: 4827111 (1989-05-01), Kondo
patent: 4906828 (1990-03-01), Halpern
patent: 5309482 (1994-05-01), Wright et al.
patent: 5930304 (1999-07-01), Hollenbeck et al.
patent: 2751148 (1998-01-01), None
patent: 40-4038588 (1992-02-01), None
patent: 40-4054688 (1992-02-01), None
patent: 40-4074290 (1992-03-01), None
patent: 40-4171592 (1992-06-01), None
Greenberg Laurence A.
Infineon - Technologies AG
Lee Diane I.
Lee Michael G.
Lerner Herbert L.
LandOfFree
Data carrier for contactless reception of data and energy,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Data carrier for contactless reception of data and energy,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Data carrier for contactless reception of data and energy,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2505455