Patent ID: 8305036

Claim:
A battery charger cradle designed to be used with a battery built-in device having an electromagnetically coupled induction coil incorporated in the battery built-in device and a battery rechargeable with a power induced by the induction coil, the battery charger cradle comprising: a primary coil connected to an AC power source for inducing electromotive force to the induction coil; a casing containing the primary coil and having a top plate, wherein the primary coil is enclosed within the casing and the battery built-in device is to be placed on a top surface of the top plate; a movement mechanism for moving the primary coil along an inner surface of the top plate, the inner surface being opposite relative to the top surface of the top plate, wherein the movement mechanism is enclosed within the casing; and a position detection controller for detecting a position of the battery built-in device placed on the top plate and controlling the movement mechanism to bring the primary coil closer to the induction coil contained in the battery built-in device, the position detection controller comprising a plurality of stationary position detection coils fixed inside the top plate of the casing, wherein, when the battery built-in device is placed on the top surface of the top plate of the casing, the position detection controller detects the position of the battery built-in device with the plurality of stationary position detection coils, the position detection controller controls the movement mechanism so that the movement mechanism moves the primary coil along the inner surface of the top plate to bring the primary coil closer to the induction coil contained in the battery built-in device.