Once Established and Commercialized, Murata's Unique Technology Will Bring About Innovation in Wireless Power Transmission
Satoshi Ishino
Director,
New Business Development Group,
Technology & Business Development Unit
After joining Murata Manufacturing in 1983, Ishino was responsible for trimmer capacitor and variable resistor technologies in the Circuit Module Dept. He worked for Murata's American subsidiary between 1987 and 1995. From 1995 to 2008, he worked on ceramic multilayer products and RF modules, before being assigned to his current position in 2008 to create new businesses. When off work, he enjoys walking at scenic locations and in traditional cultural districts.
Wireless power has been attracting increasing attention as a solution that makes mobile phones, smartphones, and tablet terminals even more convenient.
This technology makes it possible to transmit electric power to rechargeable batteries without the need for cables.
Energy transfer represents a completely new terrain for Murata.
Our engineers have come up with an innovative module, which has now been commercialized.
Murata Wireless Power Transmission Module Hits the General Market
I have been working on the development of a wireless power transmission module as part of Murata's energy business. Designed to recharge mobile phones and tablet terminals in a contactless fashion, the Murata wireless power transmission module can transfer power once a device is placed within a defined area around the module.
It features ease of introduction, a wide charging area, and low heat generation in the wireless power transmitter. We had aimed to commercialize this technology for some time before Hitachi Maxell, Ltd. introduced a Murata module into the "AIR VOLTAGE for iPad2*" in November 2011.
Wireless power transmission modules can be used in a variety of equipment, making recharging easy at home, work, and in public places.
* iPad is a registered trademark of Apple Inc.
Different Contactless Power Transmission Concepts
Three major technologies are being used to achieve wireless power transmission. The first, electromagnetic induction, transmits power using induced magnetic flux between transmitter and receiver. When the coil in the transmitter is energized, it generates a magnetic flux, which in turn generates an electric current in the receiver coil. A drawback is that any misalignment of the coils reduces transmission efficiency. Another disadvantage is that the coils in both the transmitter and receiver require relatively large space. This technology, which Murata, among others, worked on for a long time, represents a relatively old approach to contactless power transmission.
The second, capacitive coupling technology, is employed in the new wireless module from Murata. Electrodes are installed in both transmitter and receiver. As both electrodes are brought close to each other, an electric field is generated between them that is used to transmit energy. Compared with electromagnetic induction, this technology provides higher transmission efficiency and alleviates the need for precise alignment between the electrodes of the charging pad and the mobile terminal. What's more, one charging pad can be used to recharge two or more terminals. This patented Murata technology was developed in collaboration with a partner.
The third technology, magnetic field resonance, is based on semiconductor technology. Radio wave technology is a further alternative that converts radio waves received by an antenna into electric power. We have suspended the development of this technology because it doesn't allow us to take advantage of Murata's strengths.
This technology still has much room for improvement. Commercialization doesn't mean that development has been completed. On the contrary, it has really just begun.
Murata Switched to Capacitive Coupling to Meet Increasing Needs
We made an earlier start in developing electromagnetic induction. But just when a charging system for smartphones that incorporated our technology was ready for launch, an overseas manufacturer premiered a new product capable of charging three mobile terminals at the same time. The competing charger also carried a pretty low price, which left us in the dust. Around that time, an organization named Wireless Power Consortium (WPC) was established to standardize electromagnetic induction technology. It was aimed at accelerating the use of wireless power transmission by opening software and control expertise. This forced us into choosing between a competitive strategy of opening our technology or following an entirely new path.
We made the decision to cancel development of electromagnetic induction and switch to capacitive coupling, which was then being perfected as a unique Murata technology. To enhance development, the in-house open recruit system was employed to increase the team to eight members. Our technology was very popular at CEATEC JAPAN, suggesting increased public awareness of wireless power transmission, and we completed a module that Hitachi Maxell introduced in a consumer product. Pricing was the only problem. Hitachi Maxell planned to set the sales price at 15,000 yen, and we wondered if consumers would see such high value in the mere function of charging. It was launched with this concern, but in the end it managed to achieve relatively high evaluation in the market. As an engineer, however, I feel development has just started and that this technology still has much room for improvement.
Lowering Prices Through Downsizing Could Rapidly Increase Market Share
Due to its operating principles, capacitive coupling technology is thought to easily allow for smaller size and lower profile. Smaller size means lower price, and downsizing is one of Murata's strengths. Of course, additional functions such as rapid charging and mobile wallet will accelerate the use of chargers based on our wireless power transmission technology. Capacitive coupling is available only from Murata; and because we have no competitors here, I think any technical breakthrough could trigger a rapid spread.
The market for wireless power transmission will expand quickly as prices are reduced. The convenience of being able to charge mobile terminals by simply placing them around the charger is much in need at home, work, and a broad range of store locations. A possible further application would be a charger integrated into the center console of a car. Simply placing your mobile phone on the console would allow recharging while you drive. It could be used to recharge electric vehicles, too, by adapting the transformer and power supply. Unlike electromagnetic induction, it eliminates the need to align the terminal with the charger. This is going to be a great advantage that could open up a large market with a public that is very interested in contactless power transmission. This is why we are going to accelerate our technical development process even further.
Market for Wireless Technology
With an increasing need for ubiquitous applications, the market for wireless technologies is expected to grow rapidly. Wireless power transmission is one such technology. After being confined to electric toothbrushes and cordless handsets, it quickly attracted enthusiastic attention when it was introduced in a smartphone in the summer of 2011; and it has the potential to open up an enormous market after its expected introduction into electric vehicles in the future.
Wireless Power Transmission Module
The new Murata wireless power transmission module can supply 10W of power to enable contactless charging. Murata's capacitive coupling wireless power transmission modules have two sets of asymmetric dipoles consisting of active and passive electrodes positioned vertically on the transmitting and receiving sides. Power is transmitted through an induction field generated by coupling the two sets of asymmetric dipoles. This configuration ensures wireless power transmission with high positional freedom and efficiency (Patent Number: PCT/FR2006/000614).