Memory display keeps power down

Imagine a display memorizing the image it shows so only pixels have to be rewritten which content changes from frame to frame. Exactly such a display has recently been invented by Sharp based on the company’s proprietary Continuous Grain Silicon technology. For this special type of display each pixel is equipped with memory circuitry to save the image information uploaded to the display. Therefore the image information has to be rewritten only in the pixels whereas the content has changed in comparison to the previous picture frame.

With common LC displays microcontroller have to rewrite the complete screen content from frame to frame at a rate of 50 to 60 Hz even though most of the image content remains the same. Consequently standard LCDs have a power consumption which is about 130 times higher than the one of the newly developed Memory LCDs. A Memory LCD of 1.35 inches consumes about 15 W in operation whereas a standard LCD of comparable size needs about 2 mW to render an image.

In addition, the Memory LCDs provide an outstanding image quality. Different from other reflective displays, the new type of LCD does not need polarisers. Thanks to a special liquid crystal material the image is generated by the status of the pixel just changing from black to white with a reflectivity of 50%.

Due to their miniscule power consumption small size solar cells provide enough electricity to drive Memory LCDs. The new type of display is therefore an ideal solution for small size portable applications such as wrist watches, pulse meter and other fitness devices, price tags, etc. Such systems can even be designed as no-battery applications using solar cells as power supply.

Samples of the new Memory LCD are available starting Q2 2009 from Sharp sales offices in Europe.