Samsung announces double-sided LCDs

by Ken Fisher

If two heads are better than one, are two faces on a single LCD a no-brainer? Samsung today announced that it has created thin-film transistor, liquid crystal display (TFT-LCD) panels capable of showing independent images on both sides of an LCD screen. Unlike other two-faced LCDs which only show an image and its reverse on the flipside, the Samsung solution can display two different images. According to Samsung, the dual-sided LCDs have been designed primarily for use in mobile products. One obvious application would be cell phones that currently have two separate displays.

Is this a battery-life nightmare in the making? Samsung says no. Although there are two visual surfaces, the new dual-sided LCD uses one backlight. One side of the LCD also helps out with illumination, using the light trapped by one side's "transmissive mode" projection to illuminate the reflective side. Transmissive LCDs are those which are actively illuminated from behind LCDs cells, and make up most LCDs that we look at these days. Reflective LCDs are just the opposite: they rely on ambient light for illumination, and therefore are less clear and offer less contrast than transmissive LCDs. You've seen these on digital watches or on the exteriors of many flip phones (some have backlights that can be activated).

How do you display two images on a single LCD? Normal LCDs have TFT gates that each operate a single pixel, but Samsung's dual-sided LCDs put two control gates on each pixel, allowing it to control each side independently without having to double the circuitry. Complex calculations take care of the rest.

Samsung's dual-sided LCD panels

Samsung will begin mass production of a 2.6mm thick and 2.22" wide QVGA (240 x 320 pixel) dual-sided panel in the first half of this year. The company said it will show off the display at CES, so we'll be sure to check it out and ask them if they expect this technology to ever make its way outside of mobile devices.

(c) www.arstechnica.com