Scientists have developed a new “blue-phase” liquid crystal technology that triples sharpness of that offered on today’s conventional LCDs.
The next generation technology jams more pixels into small spacers, while also reducing the power needed to run the device.
Shin-Tson Wu, the lead researcher of the project at the University of Central Florida’s College of Optics and Photonics (CREOL), says that the blue-phase technology could triple resolution density to as much as 1500 ppi on the same screen sizes used today.
“Today’s Apple Retina displays have a resolution density of about 500 pixels per inch,”
“With our new technology, a resolution density of 1500 pixels per inch could be achieved on the same sized screen. This is especially attractive for virtual reality headsets or augmented reality technology, which must achieve high resolution in a small screen to look sharp when placed close to our eyes.”
Blue-phase liquid crystal technology isn’t new though, as it was first demonstrated by Samsung back in 2008, however issues with extremely high voltage and slow charging capacitors blocked the then revolutionary discovery from becoming a mainstream item.
The scientists worked with liquid crystal manufacturer JNC Petrochemical Corporation in Japan and display manufacturer AU Optronics Corporation in Taiwan, to develop a more efficient version of this blue-phase display technology.
They were able to develop a special performance-enhancing electrode structure, that could achieve light transmittance of 74 percent with an operation voltage of 15 volts per pixel – operational levels that could finally make field-sequential color displays practical for product development.
Wu’s team worked with JNC to reduce the blue-phase liquid crystal’s dielectric constant to a minimally acceptable range to reduce the transistor charging time and get submillisecond optical response time. However, each pixel still needed slightly higher voltage than a single transistor could provide. To overcome this problem, the researchers implemented a protruded electrode structure that lets the electric field penetrate the liquid crystal more deeply. This lowered the voltage needed to drive each pixel while maintaining a high light transmittance.
Today’s LCDs use a thin layer of nematic liquid crystal to modulate incoming white LED light. Thin-filmed transistors control the light output of each pixel, with each pixel containing a red, green, and blue filter (subpixels). The light output per pixel can be adjusted to display whatever combination of red, green, and/or blue, to generate one of a million different colors on the screen (when viewed as a whole).
Blue-phase liquid crystal has a huge upper hand as it can be switched, or controlled about 10 times faster than the nematic type. This sub-millisecond response time allows each LED color (red, green and blue) to be sent through the liquid crystal at different times and eliminates the need for color filters. The LED colors are switched so quickly that our eyes can integrate red, green and blue to form white.
“With color filters, the red, green and blue light are all generated at the same time,” said Wu. “However, with blue-phase liquid crystal we can use one subpixel to make all three colors, but at different times. This converts space into time, a space-saving configuration of two-thirds, which triples the resolution density.”
The blue-phase liquid crystal also triples the optical efficiency because the light doesn’t have to pass through color filters, which limit transmittance to about 30 percent. Another big advantage is that the displayed color is more vivid because it comes directly from red, green and blue LEDs, which eliminates the color crosstalk that occurs with conventional color filters.
Now that Wu and his team combined blue-phase liquid crystal with energy efficient electrode structure, they are working on building their first working prototype which they expect to publicly display some time in 2018.
The paper was published in the Optical Materials Express journal.