February 8, 2009

E-paper signs being tested in Tokyo for disaster prevention

The user of E-paper signs has been seen in test in Tokyo recently. 

Aparently they are connected by a wireless network and information can be displayed on them in case of an emergency.

"There are currently two signs: one in the lobby of the post office measures over three meters across and sports 240 x 768 resolution (the paper has 4mm pixels), and holds down power consumption at about 24W. Stationed at the Higashi-Ikebukuro bus stop, the second sign is 60 x 40 centimeters with 144 x 96 resolution, and power consumption here is about 9W."

The original post on Techon states that the ePaper was developed by Toppan Printing. The aim of the study appears to be "to prove the effectiveness of the system as evacuation guidance for people who might not be able to return home in the event of a disaster."

The biggest at 1m x 3.2m is a significant size, even if 4mm pixels, and was made by arranging 48 x 96-pixel electronic papers in five vertical rows and eight horizontal rows (40 tiles in total) and consumed 24Watts (0.6Watt per tile).

The smaller sign of only three tiles consumed more proportionally at 9Watts, presumably due to the consumption of the receiving wireless electronics being significant compared to a tile's consumption, and the same across the two sized displays. If each tile consumer 0.6Watts (say), then the electronics would be around 7Watts in this last example. I'd need to do some numbers but that seems to be able to be achieved with a solar panel attached to it, and having a battery that would give quite a few hours of operation also seems feasible.

That maybe why they have focused on emergency use cases, as it could be interesting that they can receive the information and change their content and continue to display information without using any "external" power source, as it maybe cutt-off due to emergency? We hope the source sending the information will have power....

It remains to be seen whether this technology will be applied beyond "public information" display to advertising signage. There is no mentioned of the visibility of these reflective (it is assumed) displays at night, and that would depend off-course on the ambient street ligthing or any front-light added to illuminate the sign.
The availability of color will no doubt be a big component of it's suitability for generating advertising revenue.

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