MAY 18--Researchers at IBM Corp. (Yorktown, NY; www.research.ibm.com) claim to have discovered a new process for manufacturing computer displays that can improve screen quality and viewing angles while saving manufacturing costs. As reported this month inNature, IBM has demonstrated a noncontact method that uses beams of ions to align the liquid-crystal molecules inside the flat-panel liquid-crystal displays (LCDs) used in portable and desktop computers and other electronic devices.
The first step in IBM's new method is to deposit a thin layer of diamond-like carbon instead of using a polymer substrate, Next, atoms are shot by an ion gun at an angle that push aside many of the surface carbon atoms, forming atomic-scale rows. When the rod-shaped liquid crystal molecules are added, one end of each molecule attaches to an exposed carbon atom, resulting in the alignment of all the liquid crystal molecules in the direction of the rows.
Says IBM lead scientist Praveen Chaudhari, "Display manufacturers told us that the single most important thing that science could do to improve their business was to invent a noncontact method for aligning liquid crystals. When our new process is integrated in manufacturing, it will enable new generations of high-quality, low-cost displays.'
When properly aligned, the molecules inside an LCD turn pixels on and off by twisting and rotating in response to electronic signals delivered by a computer processor. Until now, the only method to reliably align the molecules involved rubbing a polymer substrate with velvet material. When placed onto the rubbed substrate, the liquid crystals line up along the rubbing direction. Without rubbing, the liquid crystal molecules would orient in different directions and would not be controlled uniformly.
This method replaces a process discovered some 95 years ago that proved when a substrate is rubbed, it forms a pattern of aligned liquid crystals. This rubbing process has been used for building LCD displays for about 20 years.
IBM is considering licensing the patented process to other manufacturers in the $20-billion-a-year flat-panel-display industry. It expects to convert the pilot line used to develop the new technique into full production by the end of this year.
