Security system to prevent unauthorised starting of the engine of a vehicle

• US 20010035813A1
• Filed: 04/17/2001
• Published: 11/01/2001
• Est. Priority Date: 04/19/2000
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments Deutschland Gesellschaft Mit Beschrã¤Nkter Haftung (Texas Instruments, Inc.)
• Inventors: Meier, Herbert
• Granted Patent: US 6,489,886 B2
• Time in Patent Office: Days
• US Class Current: 340/5.72
• CPC Class Codes: B60R 25/04 operating on the propulsion system, e.g. engine or drive motor
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user

Abstract

A security system to prevent unauthorized starting of the engine of a vehicle has a remote control unit (18) equipped with a transponder which, on reception of an interrogation signal by means of at least one reception aerial (20), transmits an identification code group by means of a transmitter unit (40 unit. Located in the vehicle is a control unit (12) which, on actuation of a starter button (26) within the vehicle, transmits the interrogation signal, and subsequently checks the identification code group transmitted by the remote control unit. Starting of the engine will only be possible when the identification code group coincides with the code group expected by it. Connected to the reception aerial (20) is a signal detector (28) which has a reaction threshold level that can be toggled between a high value and a low value. This signal detector will relay the interrogation signal to further processing stages only when the interrogation signal level exceeds the set reaction threshold.

Claims

1. A security system to prevent unauthorised starting of the engine of a vehicle, with a remote control unit containing a transponder which, on reception of an interrogation signal by means of at least one reception aerial, transmits an identification code group by means of a transmitter unit, and a control unit located in the vehicle which, on actuation of a starter button within the vehicle, transmits the interrogation signal, and which subsequently checks the identification code group transmitted by the remote control unit and enables the starting procedure of the engine only when the identification code group coincides with the code group expected by it, comprising a signal detector (28), connected to the reception aerial (20), whose reaction threshold can be toggled between a high and a low value, and which relays the interrogation signal for further evaluation only when the interrogation signal level exceeds the set reaction threshold, a code verification circuit (32), connected to the signal detector (28), which checks the interrogation signal relayed by it as to whether it contains a pre-established code group and, on recognition of this code group, switches the reaction threshold of the signal detector (28) to its high value, whereby the code verification circuit (32) will cause the transmitter unit (40) to transmit the -identification code group only when it receives the interrogation signal, even after the signal detector (28) has switched over to its high reaction threshold level.

2. Security system according to

claim 1

, where the remote control unit (18) comprises two further reception aerials (20a, 20b) which are spatially arranged in such a way that the main reception directions (x, y, z) of each of the three reception aerials (20, 20a, 20b) are aligned to a different one of each of three mutually perpendicular spatial axes, and that each of the two further reception aerials (20a, 20b) is connected to a signal detector (28a, 28b) of the same type as the signal detector (28) connected to the first reception aerial (20).

3. Security system according to

claim 2

, where the reaction threshold levels of the signal detectors (28, 28a, 28b) are adjustable to suit the spatial conditions of the intended environment of use of the remote control unit (18).