According to U.S. media, China’s optoelectronic engineers have manufactured a special liquid crystal display (LCD) that is light, thin, papery, flexible, and strong. Using this LCD, newspaper content can be uploaded to a flexible, ultra-thin display and updated daily in real time. This sounds like something of the future, but scientists estimate that the display's production costs are low, and the cost of a 12.7-cm display may be as low as $5 (about 31 yuan - this site's note). The US "Applied Physics News" half-monthly this week reported on this new type of optically-controllable rewritable LCD design.
The United States Daily Science website reported on March 28th that the research team focused on achieving two key innovations in highly flexible design. The first is a newly developed light-controlled rewritable LCD. Like the ordinary LCD, the optically-controllable rewritable LCD is structured like a sandwich, that is, the two substrates are filled with liquid crystals. The difference is that the electrical connection on the common LCD substrate generates an electric field that causes a single pixel to turn bright and dark, whereas the optically-controllable erasable LCD covers the substrate with special molecules that are rearranged and switched by the polarized light. This eliminates the need for conventional electrodes, reduces the size of the structure, and allows more choices for the type and thickness of the substrate. Therefore, the light-controllable rewritable LCD is thinner than the conventional LCD and has a thickness of less than 0.5 mm. It can be made of a flexible plastic and weigh only a few grams. Sun Jialu, a co-author of the research report and of Donghua University, said: "It's only a little thicker than paper."
According to reports, the optically-erasable LCD has a simple structure and is therefore more durable and less expensive to manufacture. In addition, like e-paper screens in e-books, energy is consumed only when converting images and text. Therefore, this new type of LCD has a low operating cost since no power is required to hold the image after the image is displayed on the screen.
The second innovation involves the separation of plastic or glass substrate spacers. Sun Jialu said that placing spacers between the glass layers can keep the liquid crystal layer uniform. All LCDs use spacers to determine the thickness of the liquid crystal. Uniform thickness ensures good contrast, response time and viewing angle. However, when the substrate is bent, the liquid crystal is pressed away from the impact point, causing blankness in certain areas of the screen. Therefore, changing the design of the spacer is essential to prevent the excessive movement of the liquid crystal in the flexible LCD. Developing a flexible design that overcomes this obstacle has proved challenging.
The researchers tried three different spacer designs and found that a grid spacer prevents liquid crystal flow when the LCD is bent or hit. This innovation led them to develop the first flexible optically-controlled rewritable LCD.
According to reports, there is another innovation that involves improving color rendering. The scientists said that prior to this study, the light-controllable rewritable LCD could only display two colors at a time. Today, their light-controlled rewritable LCDs can display optical primary colors simultaneously. They do this by using a special type of liquid crystal that reflects red, green and blue in the LCD. To make it a commercial product, Sun Jiasheng hopes to increase the resolution of flexible optically-controllable rewritable LCDs.