Transponder key with rechargeable internal battery

摘要

A transponder key 16 for a security system, e.g. vehicle door lock and ignition system, comprises a rechargeable internal battery 16d and means 16a, 16b for inhibiting the transmission of signals from the key in response to detection of a charging voltage for recharging the internal battery of the transponder. A storage station 20 comprising a battery charger 22 suitable for recharging the internal battery 16d of the transponder key 16 is also disclosed. Preferably the charging voltage is applied to the key 16 by means of electrical contacts, or is induced electromagnetically in a coil provided within the key. The key 16 may include means for rectifying the induced voltage to generate the charging voltage for the internal battery. Preferably the storage station includes a radio shield surrounding the key to prevent it from receiving or transmitting signals whilst in storage.