1. Field of the Invention
The present invention relates to a non-contact electric power transmission apparatus and an electric appliance which includes the non-contact electric power transmission apparatus.
2. Description of the Background
Referring to FIG. 12, a non-contact electric power transmission apparatus (T) has a primary unit (T1) and a secondary unit (T2). A battery charger has the primary unit (T1). An electric appliance has the secondary unit (T2). When the electric appliance is placed on the battery charger, the primary unit (T1) and the secondary unit (T2) face each other. The primary unit (T1) of FIG. 12 has a primary core (C1), a power primary winding (L1), and a signal secondary winding (L3). The primary core (C1) has a U-shape. The signal secondary winding (L3) is wound around the power primary winding (L1) coiled around the primary core (C1). The secondary unit (T2) of FIG. 12 has a secondary core (C2), a power secondary winding (L2), and a signal primary winding (L4). The secondary core (C2) has a U-shape. The signal primary winding (L4) is wound around the power secondary winding (L2) coiled around the secondary core (C2). When the electric appliance is placed on the battery charger, the facing surface of the primary core (C1) and the facing surface of the secondary core (C2) face each other. Electric power and signal are transferred between the primary unit (T1) and the secondary unit (T2) through electromagnetic induction. The electric power has a frequency of 50 kHz and the control signal has a frequency of 1 MHz.
In the conventional non-contact electric power transmission apparatus (T), the leakage flux from the power primary winding (L1) affects the signal induced in the signal secondary winding (L3). Likewise, the leakage flux from the power secondary winding (L2) affects the signal supplied to the signal primary winding (L4).
According to one aspect of the present invention, a non-contact electric power transmission apparatus includes a primary unit and a secondary unit. The primary unit includes a primary core, at least one power primary winding and at least one signal secondary winding. The primary core has a first facing surface and a first winding axis substantially parallel to the first facing surface. The at least one power primary winding is wound around the first winding axis of the primary core. At least one signal secondary winding is wound around the first winding axis of the primary core and provided to be apart from the at least one power primary winding to form a primary gap between the at least one power primary winding and the at least one signal secondary winding. The secondary unit includes a secondary core, at least one power secondary winding and at least one signal primary winding. The secondary core has a second facing surface and a second winding axis substantially parallel to the second facing surface. The at least one power secondary winding is wound around the second winding axis of the secondary core. The at least one signal primary winding is wound around the second winding axis of the secondary core and provided to be apart from the at least one power secondary winding to form a secondary gap between the at least one power secondary winding and the at least one signal primary winding. The secondary unit is configured to be placed with respect to the primary unit such that the second facing surface faces the first facing surface and such that the at least one power secondary winding and the at least one signal primary winding are electromagnetically connected to the at least one power primary winding and the at least one signal secondary winding, respectively.
According to another aspect of the present invention, an electric appliance includes a primary unit and a secondary unit. The primary unit includes a primary core, at least one power primary winding and at least one signal secondary winding. The primary core has a first facing surface and a first winding axis substantially parallel to the first facing surface. The at least one power primary winding is wound around the first winding axis of the primary core. At least one signal secondary winding is wound around the first winding axis of the primary core and provided to be apart from the at least one power primary winding to form a primary gap between the at least one power primary winding and the at least one signal secondary winding. The secondary unit includes a secondary core, at least one power secondary winding and at least one signal primary winding. The secondary core has a second facing surface and a second winding axis substantially parallel to the second facing surface. The at least one power secondary winding is wound around the second winding axis of the secondary core. The at least one signal primary winding is wound around the second winding axis of the secondary core and provided to be apart from the at least one power secondary winding to form a secondary gap between the at least one power secondary winding and the at least one signal primary winding. The secondary unit is configured to be placed with respect to the primary unit such that the second facing surface faces the first facing surface and such that the at least one power secondary winding and the at least one signal primary winding are electromagnetically connected to the at least one power primary winding and the at least one signal secondary winding, respectively.