Communications: electrical – Land vehicle alarms or indicators – Of burglary or unauthorized use
Reexamination Certificate
1999-08-09
2001-12-11
Crosland, Donnie L. (Department: 2632)
Communications: electrical
Land vehicle alarms or indicators
Of burglary or unauthorized use
C340S425500, C340S870030, C307S010200
Reexamination Certificate
active
06329909
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a code signal generator, in particular for an anti-theft protection system of a motor vehicle.
A prior art code signal generator (European Patent Application EP 0 659 963 A1) has a transponder unit, which receives a question code signal from a transmitting and receiving (transceiver) unit disposed in the motor vehicle. In response, a response code signal is generated in the code signal generator with the aid of the question code signal and transmitted back to the transmitting and receiving unit in the motor vehicle. In the event of authorization of the response code signal (authentication) an immobilizer of the motor vehicle is released.
In addition, the code signal generator has a remote control unit, which is independent of the transponder unit, generates a coded control signal after the actuation of a pushbutton switch and transmits the signal via an antenna. A receiving unit in the motor vehicle receives the coded control signal and controls the central locking system if the control signal is authorized.
In this case, the transponder unit and the remote control unit are arranged independently of one another on a key grip. Each unit has a computing unit which respectively generates is the response code signal and the control signal.
A further known code signal generator (International Application WO 96/17290) has either a transponder unit or a remote control unit. Only the remote control unit is required in the event of unidirectional signal transmission, and only the transponder unit in the event of bidirectional signal transmission. To make it more difficult to intercept the transmitted signals, the same signal is transmitted via at least two different transmission channels. The code signal generator therefore has two different transmitters. The two received signals must be correct in order to enable a security unit to be controlled.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a code signal generator, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which has as few components as possible yet permits authentication which is interception-proof and falsification-proof.
With the foregoing and other objects in view there is provided, in accordance with the invention, a code signal generator for triggering a security unit, particularly in a motor vehicle, comprising:
a transponder unit adapted to receive a question code signal from a stationary transmitting and receiving unit, to generate, in response, a response code signal based on the question code signal, and to transmit the response code signal to the transmitting and receiving unit for authentication, whereby a security unit is enabled upon a successful authentication;
transmitting unit independent of the transponder unit, the transmitting unit having a switching element, and being adapted to wirelessly transmit a control signal to the stationary transmitting and receiving unit upon actuation by the switching element and, upon authorization, to remotely control other controllers; and
a single signal generating unit accessible by the transmitting unit and by the transponder unit for generating the control signal and the response code signal.
In other words, the code signal generator has a single encryption unit which is accessed both by a remote control unit and by a transponder unit. Consequently, a coded control signal and an response code signal are respectively generated by the encryption unit and transmitted.
It is particularly advantageous if the transponder unit, the remote control unit and the encryption unit are disposed as a circuit in an integrated manner on a semiconductor chip. The code signal generator has only small dimensions as a result of this. The code signal generator may have a resonant circuit with a coil and a capacitor, by means of which signals are transmitted or received inductively. At the same time, it also has one or more transmitters by means of which the coded control signal is transmitted in a wireless fashion.
The code signal generator may have an energy store which is charged by wirelessly received energy signals. Consequently, the code signal generator does not require any battery that has to be repeatedly replaced as soon as its capacity has been exhausted.
In accordance with an added feature of the invention, a control unit controls the transponder unit and the transmitting unit in dependence on a received question code signal and the actuation of the switching element, respectively.
In accordance with an additional feature of the invention, the transponder unit, the transmitting unit and the signal generating unit are circuits commonly integrated on a semiconductor chip.
In accordance with another feature of the invention, the transponder unit includes a resonant circuit with a coil and a capacitor for inductively transmitting the response code signal and inductively receiving the question code signal.
In accordance with a further feature of the invention, the transmitting unit includes a modulator and a radio antenna for transmitting the control signal coming from the modulator and an RF oscillator.
In accordance with again an added feature of the invention, the transmitting unit has an optical transmitter for optically transmitting the control signal.
In accordance with again an additional feature of the invention, the code signal generator includes a memory unit connected to the transponder unit, the memory unit being enabled for data to be written but disabled for data to be read from externally of the code signal generator.
In accordance with again another feature of the invention, synchronization data are stored in the memory unit, and the synchronization data are fed to the signal generating unit for generating one of the response code signal and the control signal, the synchronization data in the question code signal being transmitted to the code signal generator, and overwriting previously stored synchronization data.
In accordance with again a further feature of the invention, a clock recovery unit is provided for recovering a clock signal for the control unit from the received question code signal.
In accordance with a concomitant feature of the invention, the stationary transmitting and receiving unit is integrated in a motor vehicle anti-theft protection system, and the security unit is an immobilizer of the motor vehicle. More specifically, with the above and other objects in view there is provided, in accordance with the invention, an anti-theft protection system of a motor vehicle, comprising:
a transmitting and receiving unit stationary in a motor vehicle;
a code signal generator for triggering a security unit of the anti-theft protection system, the code signal generator including a transponder unit adapted to receive a question code signal from the stationary transmitting and receiving unit, to generate, in response, a response code signal based on the question code signal according to a given algorithm, and to transmit the response code signal to the transmitting and receiving unit for authentication;
a transmitting unit independent of the transponder unit, the transmitting unit having a switching element, and being adapted to wirelessly transmit a control signal to the transmitting and receiving unit upon actuation by the switching element; and
the transmitting and receiving unit having a signal generating unit generating a desired code signal according to the given algorithm, wherein one of the received response code signal and the received control signal are compared with the desired code signal and wherein, if the response code signal or the control signal corresponds with the desired code signal at least to a large extent, an enable signal is generated for controlling a security unit in the motor vehicle.
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 embod
Schrey Ulrich
Siedentop Michael
Crosland Donnie L.
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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