Fujitsu modulates RGB LED sources to convey data to cell phones

Technology demonstration allows RGB SSL products to send data about objects being illuminated in applications such as retail and museums.

Fujitsu modulates RGB LED sources to convey data to cell phones
Fujitsu modulates RGB LED sources to convey data to cell phones

Technology demonstration allows RGB SSL products to send data about objects being illuminated in applications such as retail and museums.

Fujitsu Laboratories Ltd, based in Kawasaki, Japan, has announced a technology development in which colored solid-state lighting (SSL) products using RGB (red, green, blue) LEDs can convey data to mobile phones and tablets. To be formally unveiled at the Fujitsu Forum in Munich, Germany this week, the technology is designed for SSL products that light objects such as retail goods or museum pieces while also delivering data about the object that mobile-device cameras can decode. The modulation is not detectable by the human eye.

Fujitsu modulates RGB LED sources to convey data to cell phonesFujitsu modulates RGB LED sources to convey data to cell phones

There have been a number of announcements in recent years about using LEDs to convey data. Several companies have demonstrated modulation of white LEDs to deliver data to computers much the way Wi-Fi works in the RF spectrum. Moreover, companies such as ByteLight and GE Lighting plan to use LEDs to supply indoor location data to mobile devices for applications such as retail.

Fujitsu, however, seems to have a different idea about how the data modulation would be used. In a museum, for example, a visitor might direct the mobile-phone camera at a work of art and receive data from the SSL fixture illuminating the art. The company said that physically affixing information to such an object can "diminish the appearance of the object itself." But the data transfer would be invisible in terms of a person viewing the object.

Fujitsu believes that the technology is scalable and could even be used to deliver data on extremely large items such as buildings. The potential range of applications is indeed broad. For example, the company said a person watching a singer could point their mobile phone camera at the performer and perhaps get an instant download of the song being performed. The company said that it will commercialize the technology in 2015.

It's not clear why the Fujitsu approach requires RGB LEDs as opposed to simply modulating phosphor-converted white LEDs. Apparently, part of the issue is that the camera has an inherently more difficult time detecting light reflected from an object as opposed to schemes such as the one from ByteLight where the expectation is that the white light goes directly from the LEDs into the camera. Indeed, any object absorbs some amount of the light and reflects some portion of the light. See our series of articles on color science to understand how light is reflected by objects. Part of the Fujitsu innovation is reflectance compensation in software that allows the camera to capture a weakened signal.

In any case, the tie to RGB LED sources will limit applications for the technology. For example, most retail stores will use LED lighting based on phosphor-converted white LEDs as opposed to more complex and expensive RGB LEDs. Fujitsu has not said how the technology will come to market, but clearly a lighting company will have to integrate support into RGB fixtures.

More in Color Tuning