Anti-theft device using code type transponder

DETAILED DESCRIPTION It is therefore an object of the present invention to provide a method and a device with which it is possible to register a new key having a code type transponder.
The above object is achieved according to an aspect of the present invention by providing a method for registering a new key in an anti-theft device including preparing a new key having a transponder in which authentication data has not been written, conducting communication between a transponder of a registered key and an electronic control unit having an anti-theft function, and determining if the communication was conducted correctly, enabling registration of a new key when it is determined that the communication was conducted correctly, and, when registration of a new key is enabled, conducting communication between the transponder of the new key and the electronic control unit and writing registered key authentication data stored in the electronic control unit into the transponder of the new key.
In this way, by using the authentication data of the master key stored in the ECU, even a new key having a code-type transponder can be appropriately registered.
By making the collation of a pre-registered master key a condition of registration of a new key it is possible to set a restriction on the registration of new keys.
That is, for example, when the anti-theft device is applied to a vehicle, in the case of a rental car or and the like a registered key is loaned out together with the vehicle for the rental period, but if this registered key is not a master key then new keys being registered unlawfully using this loaned-out registered key can be prevented.
Whether each of a number of electronic keys having the same authentication data is a master key or a sub-key can be distinguished by means of a key identification code assigned uniquely to each key.
Other objects and features of the present invention will appear in the course of the description thereof, which follows.