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Capacitive Coupling Wireless Power Transmission System

Murata has entered the mass-production stage of capacitive coupling wireless power transmission modules (includes transmission module and reception module in a set) capable of transmitting 10W of energy. Electric equipment such as mobile equipment may be recharged by building a transmission module in the recharging stand and a reception module in the equipment to be recharged.

The capacitive coupling wireless power transmission system is constructed by vertically positioning two sets of asymmetric electric dipoles, with active and passive electrodes on the transmitting side and active and passive electrodes on the receiving side. Power is transmitted through an induced electric field generated by coupling these two sets of asymmetric electric dipoles. This configuration contributes to high-efficiency wireless electric transmission characteristics with position freedom.

Its transmitting side consists of a transmission module and a transmission electrode, and the receiving side consists of a reception module and a reception electrode. The transmission module is made up of an inverter produced with Murata's own power supply circuit design technology and a control circuit to ensure safety.

Mass-produced module LXWS series
(10W output type)

Electric power is converted to AC by the transmission module and is transmitted to the receiving side through a capacitor consisting of transmission and reception electrodes. The reception module, consisting of a rectifier circuit and voltage converter circuit, supplies a stable direct current to the batteries and equipment.

This system is characterized by following three points.

Having a wide high-efficiency charging area
Especially because of the freedom of its position in the horizontal direction, this system can recharge equipment anywhere on the recharging stand.
Ease of introduction
Wireless recharging is realized without compromising equipment design due to extremely thin electrodes at a few μm for both transmission and reception electrodes.
Absence of heat generation in the wireless transmission region
Current flowing through the area of electrodes at a few mA, one of variables for determining Joule heat, is too small to generate a significant amount of heat. This makes it possible to position the wireless power transmission region near a battery, due to absence of temperature escalation.

We commenced mass production of the iPad2 accessory implementing this technology for the first time in autumn of 2011. We also conducted a series of demonstrations stressing the characteristics described above at CEATEC JAPAN 2011 and CES 2012. We will engage in development to implement this technology to various equipment including smartphones, mobile music players, digital cameras, tablets, notebook PCs, toys, lightings and household facilities.