Reflective twisted nematic w:liquid crystal display.
1.Vertical filter film to polarize the light as it enters.
2.Glass substrate with ITO electrodes. The shapes of these electrodes will determine the dark shapes that will appear when the LCD is turned on. Vertical ridges are etched on the surface so the liquid crystals are in line with the polarized light.
3.Twisted nematic liquid crystals.
4.Glass substrate with common electrode film (ITO) with horizontal ridges to line up with the horizontal filter.
5.Horizontal filter film to block/allow through light.
6.Reflective surface to send light back to viewer.
Image source: LCD layers.svg by Ed g2s is licensed under CC BY 3.0
Two Ohioans have had a great impact on the liquid crystal display (LCD) market. James Fergason of Kent State University, in 1969 discovered the twisted nematic field effect of liquid crystals, which led to a better LCD, used in pocket calculators, digital wristwatches, and computer displays. And, John L. Janning, of Dayton, discovered a way to permanently align molecules in liquid crystal materials. It opened the way to large-scale manufacture of liquid crystal displays in the early 70's. Janning’s 250 other inventions include "Stay-Lit" Christmas lights.
The technology of LCDs were first integrated into watches and calculators, but have now impacted many industries from medical to industrial equipment, and consumer electronics, toys, and accessories.
Fergason's Impact
In 1970, James Fergason made the first operating LCDs. Previously, LCDs required a lot of power and worked for only a limited time. They also had poor contrast, making them a bit hard to read. Fergason joined the Liquid Crystal Institute at Kent State University during the 60s. While serving as Associate Director there, Fergason discovered the twisted nematic field effect of liquid crystals. He then left the University and founded his own company, International Liquid Crystal Company (ILIXCO), in Kent, OH. Fergason then focused on developing an improved display, based on the twisted nematic field effect. The result was a longer lasting, easier to read device, which became the industry standard.
Fergason did not make a patent application at the time, however, and two men (Wolfgang Helfrisch and Martin Schadt) who worked at F. Hoffmann La Roche in Basel, Switzerland, published a paper on the same effect in 1971. Later, Hoffmann La Roche purchased Fergason's patent rights.
About Janning
John L. Janning of Dayton, Ohio, has over 50 U.S. Patents and 250+ worldwide. He began his career at NCR, and then launched his own business - JLJ, Incorporated - to focus full time on his research and inventions. Janning developed the liquid crystal molecular alignment invention which improved the display and made large scale manufacturing a profitable venture. In addition to his work on LCDs, Janning also invented the thermal printing wafer, which is used in thermal fax machines, and the familiar orange plasma displays seen in many checkout counters. Another invention is the Stay Lit® Christmas light set, which incorporates a microchip into each socket that regulates the voltage across each socket. This technology keeps a string of lights bright even if there are broken, loose, or burned out bulbs.
What is an LCD?
A modern tablet computer, one of numerous uses for the LCD. Image source: Tablet and Keyboard Dock by Dinominant is licensed under Public Domain Dedication CC0 1.0
LCD stands for Liquid Crystal Display -- a special type of display that is used on portable computers, digital watches, and other products. LCDs incorporate two sheets of special polarized materials with a liquid crystal solution sandwiched between. When an electric current is passed through the liquid, it causes the crystals to align themselves so that light cannot pass through. Each crystal behaves like a miniature shutter, able to either block or allow light to pass through.
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