Built-in memory slashes LCD power consumption
Sharp has used its continuous-grain method for making liquid crystal displays (LCDs) to cut the power consumption of small screens a hundredfold.
Because the technique makes it possible to construct more complex electronic circuits on glass than conventional methods, the company has been able to couple the liquid-crystal elements to memory cells so that a controller only needs to rewrite pixels when the image needs to change. Conventional design demand that the controller updates each LCD pixel 50 or 60 times a second even if the image is static.
The I/O drivers need on the controller consume a lot of the power attributable to the display, if the backlight’s contribution is ignored. The result is that standard LCDs have a power consumption which is more than 100 times higher than the one of the memory LCDs, according to Sharp.
A Memory LCD measuring 1.35in diagonally consumes about 15 µW in operation whereas a standard LCD of comparable size needs about 2 mW to render an image.
Sharp has redesigned the display itself to not need polarisers. The pixel has a reflectivity of 50 per cent, the company claimed. A small solar cells should provide enough electricity to drive the Memory LCDs, suiting them to use in wristwatches and fitness devices as well as shelf-mounted price tags.
Samples of the new Memory LCD will be available by the end of the month.