Series List

The Sparkling Therometer Project

What is Visible Light Communication?

How to Create a Thermometer

The Experimental Method

2015 International VLC Workshop

Make Your Very Own Thermometer!

Making Jewelry

Making a "Disco KURUMI"

Making a Planetarium

Making a Bird’s Nest

Concluding the Workshop



Yumiko Kodama

Environmental Sculptor, Lighting Designer/LED Artist
Creator of lighting for the Nagano Olympics’ award ceremonies
Creator of Hokusai’s Red
Mt. Fuji for the Chunichi Shimbun Pavilion at Expo 2005 Aichi.

Also created the Visible Light Communication Monument for the Beijing Olympics, and is currently researching “Olympic IT Strategies” at the National Institute of Informatics.


Now that we’re familiar with LEDs, let’s take a look at new LED technology. The thing about LED is that it always flickers. When the flickering is slow enough, you can actually see the light blinking. When it happens at a speed of 3 millions times per second, you cannot see it with your own eyes, but you can see the pretty LED color.

In 2000, Professor Emeritus Masao Nakagawa of Keio University discovered that LEDs can transmit Morse Code; he then collaborated with many communications companies to establish a research entity, and spread his finding throughout the world. This transmission is called LED Visible Light Communication. Sources of illumination like fluorescent lights are not able to transmit information, but LED can do so brilliantly.

How does that relate to KURUMI?

Researchers have produced a handful of techniques, and last autumn, one of these techniques led to the creation of the KURUMI circuit board. When LED lights flash on the board, it’s not just any old flickering; it’s actually a signal.

Casio Computer Co., Ltd., the famous watch company, developed a technique known as “picalico” which allows a camera to receive this LED-transmitted information. Let’s try adding to that so we can make our very own smartphone thermometer capable of detecting the temperature. If you turn the pink circuit board over, you will see that a temperature gauge is built into the back. The numerical temperature at a particular spot is converted into a signal which can be read by an image sensor, a component of almost any digital camera. From there, it passes through the Internet into a place resembling a huge information vault which is known as the “cloud,” and when the number representing the information is given, the “vault” can be entered and the information retrieved, and the message “28 degrees” can be sent to our smartphone. We cannot see that process with our eyes, making it difficult to understand.

However, gadgets we always use like our smartphones employ infrared data communication which we cannot see at all, so Visible Light Communication which we can see is safe. This is because information is communicated strictly within the range of visible light. Telephone fraud has been rather easy to do, since we have been unable to see the world of information transmission, but our assumption that transmissions must be invisible was wrong! Visible Light Communication does not emit electromagnetic waves, and it is beautiful and safe, so I think its usage will continue to spread. And I thought of another point in its favor. Visible Light Communication will help you converse smoothly underwater.

Continue on to learn How to Create a Thermometer.