Murata Manufacturing Co. Ltd. and Seiko Epson Corp. announced that they will start the joint development of non-contact quick charging system.
The development will be promoted based on Seiko Epson's non-contact charging technology and Murata's technique for making Li-ion batteries suitable for quick recharging. Targeting use in mobile phones, etc., they aim to ship samples in 2008 and start mass production in 2009-2010. The prototype non-contact charging system will be on display at CEATEC JAPAN 2007 from Oct. 2-6, 2007.
Power transmission efficiency 70%
The non-contact charging system slated for joint development leverages electromagnetic induction. The charger stand and the mobile device are respectively equipped with coils that generate power by electromagnetic induction. Seiko Epson will mainly focus on the development of the charger stand (transmitting side, or primary side), while Murata will be involved in the production of Li ion rechargeable battery. Their goal is to recharge a mobile phone in about 10-15 minutes in a non-contact manner. For this purpose, the system will be designed to supply a large current of more than 3 A at a time of recharging, said the companies.
"The secondary battery and the mobile device will not generate heat," claimed Murata. "We will be able to provide a safe battery."
The non-contact power transmission system, which will be the core of this product, is based on Seiko Epson's proprietary AirTrans technology. This technology relates to a non-contact charging system intended for mobile devices. It includes techniques for foreign matter inspection, ID authentication and coils. Meanwhile, Murata will develop the quickly rechargeable battery, module and power source designs, magnetic field shielding technology, etc.
As for the quickly rechargeable Li ion battery in the latest system, the two companies plan to employ the product that is currently under joint development by Murata, Enax Inc. and others. It is expected to be a laminate Li ion rechargeable battery using lithium manganate (LiMn2O4) for the positive electrode.
The mass production technology used for Murata's laminated ceramic capacitor will be applied to the development of the rechargeable battery, the companies said.
Murata and Epson aim to increase the power transmission efficiency to about 70%.
"The power transmission efficiency of existing systems is only about 30% on average and barely reaches 50% at the highest level," said Seiko Epson.
Meanwhile, Seiko Epson developed another non-contact charging system besides the joint development with Murata and announced that the volume shipment of the 2.5-W class product is slated for launch as early as in May 2008.
At the press conference, the two companies also conducted the demonstration of recharging by using the box-shaped prototype system. It is equipped with a Li ion rechargeable battery with a current capacity of about 800 mAh and a non-contact recharger.
The demonstration showed that the recharging can immediately be started simply by placing the prototype on the charger stand. A current as large as 3 A was used to fully recharge the battery only in about 15 minutes.
According to the companies, a power transmission of 95% or higher is ensured between the transmission and reception coils of the prototype. Although substantially no heat is generated in the coil portions, the temperature rises to a certain degree in part of the power supply circuit, the companies said. Thus, they intend to take appropriate measures against this problem.