AU Optronics (AUO) Corp showcased a device made by attaching a flexible thin-film photovoltaic (PV) battery to the back of flexible electronic paper (e-paper) at FPD International 2011.
The company calls the device "Un-plugged Flexible E-paper Display," meaning that it does not require a power plug.
The combination of PV battery and e-paper, whose power consumption is small, has been considered promising for some time. And a wristwatch equipped with both of them has already been released.
This time, AUO employed flexible products for both e-paper and PV battery to develop e-paper that operates without an external power supply.
The size and pixel count of the e-paper are 6 inches and 800 x 600 (SVGA), respectively. Though the display technology used for the e-paper is EPD (electronic paper display), which is commonly used, AUO employed organic TFTs. The e-paper is driven at a frequency of 50Hz. The thickness of the panel is 0.127mm.
The e-paper comes with an amorphous silicon PV battery, which measures 132 x 212 x 0.3mm and weighs 10g as a module. With 1.5AM (air mass) solar light, it generates 1W or more of electricity. In other words, its conversion efficiency is about 3.6% or higher. The output voltage at the time of power generation is 12V.
The exhibited device was made by combining the e-paper and the battery. Also, it was equipped with an external rechargeable battery.
To refresh the screen of e-paper, several hundred milliwatts of electricity is required even for a short period of time. Therefore, the new e-paper device can be driven without a rechargeable battery when its PV battery is exposed to direct sunlight. But it requires a rechargeable battery when it is used under room light, etc.