Sensor technology that requires no batteries or wiring

"No batteries, no wiring, no maintenance. EnOcean wireless communication technology with these characteristics is the best choice for acquiring various data in fields such as infrastructure management and health care." With this idea in mind, semiconductor company Rohm will use EnOcean's wireless communication technology to develop business related to acquiring big data.

　　EnOcean is a fabless venture company that provides semiconductor products and was founded in 2001 by former Siemens employees. Although it is a venture company, its strength should not be underestimated. The industry group "EnOcean Alliance" that promotes the development of EnOcean technology has more than 300 member companies around the world, including about 30 Japanese companies such as Murata Manufacturing, Omron, and Taiyo Yuden.

　　Used in more than 250,000 buildings

　　Mitsuharu Taniuchi of Rohm's R&D headquarters said that the reason most companies adopt EnOcean technology is that "Among technologies for sensor networks, EnOcean is clearly superior to other wireless communication technologies." The biggest advantage of this technology is that it does not require batteries (Figure 1). EnOcean technology is specially developed for sensor networks, and the energy required for communication is much less than other wireless communication technologies. Specifically, the power consumption is less than 1/10 of ZigBee, less than 1/100 of Bluetooth, and less than 1/1000 of WiFi.

　　Equipped with functions such as energy conversion and sensors, the wireless sensor module does not require batteries.

　　EnOcean not only consumes less energy, but also has the characteristics that other wireless communication technologies do not have, which is the use of energy harvesting (environmental power generation) technology. It can use the energy converted from motion, vibration, temperature, light, etc. for wireless communication. Therefore, EnOcean does not need batteries.

　　The EnOcean market has already taken shape, with more than 250,000 buildings, including schools, office buildings, airports, stations, and factories, mainly in Europe and the United States, adopting this technology*1, and more than 100 companies have launched more than 1,000 products compatible with EnOcean technology (Figure 2). Compared with previous wireless switches, these products have the characteristics of not requiring built-in batteries.

　　1 Japan's office buildings, shopping malls, factories, etc. have also begun to adopt it.

　　For example, lighting switches using EnOcean technology use the energy generated by the switching action to wirelessly transmit signals and do not require batteries. Sensors that detect the open and closed status of doors and windows use the weak light in the room to generate electricity and wirelessly transmit switch information, also without the need for batteries.

　　Priority in supporting Platinum bands

　　While many companies have launched products using EnOcean technology, Rohm's efforts to develop EnOcean technology have attracted attention. In October 2012, Rohm became the promoter of the EnOcean Alliance. Including Rohm, there are only nine promoters in the world, and only one in Asia. In other words, Rohm is the core of the development of the huge Asian market and has a wide space to exert its strength. In fact, Rohm has already started selling EnOcean products to customers in Japan and other parts of Asia in April 2013.

To this end, the company is now vigorously developing EnOcean products that use the platinum band, which has excellent transmission characteristics, that is, the 928MHz band. According to standard requirements, current EnOcean products in Japan need to use the 315MHz band. When using the 315MHz band, the communication distance of EnOcean products is about 30m. Although the communication distance is farther than ZigBee (about 15m), Bluetooth (about 10m), and WiFi (10-15m), there is no decisive difference.

　　If the 928MHz band is used, the communication distance can be extended to about 100m. Moreover, for EnOcean products in the 928MHz band, "ROM currently has priority in sales" (Mitsuharu Taniuchi)*2. The company aims to start mass production around the end of 2013. This will clearly differentiate ROHM's products from other companies that sell EnOcean products.

　　2 Rohm is actively working as a promoter to include the 928MHz band in the EnOcean standard, which is expected to give the company an advantage.

　　Targeting infrastructure monitoring

　　In addition to adopting new frequency bands, ROHM has also envisioned a promising use for EnOcean technology to obtain big data, such as monitoring infrastructure such as bridges and highways. That is, a large number of devices such as acceleration sensors using EnOcean technology are installed on these infrastructures to measure vibration values ​​and other data at any time*3.

　　3 Once an abnormality is detected, detailed inspection and maintenance can be carried out immediately.

　　EnOcean technology, which does not require batteries, is an ideal choice for sensors installed on infrastructure because "infrastructure that affects human life cannot afford to have sensors that stop working due to battery exhaustion. However, if batteries are frequently replaced to avoid this, maintenance becomes troublesome" (ROHM).

　　The application of EnOcean technology to infrastructure also faces problems. Even if the 928MHz frequency band is used to extend the communication distance to about 100m, it cannot meet the needs. Therefore, Rohm is exploring whether it is possible to extend the communication distance of EnOcean technology to about 1km using the 928MHz frequency band.

　　The key to achieving this is how to effectively utilize the limited electrical energy created by energy harvesting technology. ROHM's policy for this purpose is to actively adopt its own technology. For example, ROHM has its own technology, semiconductor non-volatile logic technology. The logic circuit of the current semiconductor is volatile, and the power supply must basically remain on all the time. If non-volatile logic technology is used, the power supply can be turned off in the normal state, and the power supply can be turned on only during processing, and then turned off immediately after the processing is completed. Using this technology, the power consumption of EnOcean products can be greatly reduced.

　　Emphasis on body area network for medical treatment

　　In addition to infrastructure, Rohm is also optimistic about another use of acquiring big data, which is the body area network (BAN) for short-range wireless communication networks in the fields of medical and health care. For example, a band-aid type sensor based on EnOcean technology is attached to the skin to collect human data such as pulse and body temperature. Although this use does not require a long communication distance like infrastructure, "the characteristic of lower power consumption than other wireless communication technologies can play a role when the communication distance is the same" (Rohm).

　　The problem with using EnOcean technology in BAN is that it is difficult to generate electricity through energy harvesting. This is because "it is difficult to apply solar power generation when using it on the skin, and it is not easy to effectively convert vibration into electricity" (Rohm). For this reason, Rohm is currently studying methods such as equipping it with button batteries.