"Today's Apple Retina displays have a resolution density of about 500 pixels per inch," said Shin-Tson Wu from the University of Central Florida's College of Optics and Photonics. "With our technology, a resolution density of 1500 pixels per inch could be achieved."
Although the first blue-phase LCD prototype was demonstrated by Samsung in 2008, the technology still hasn't moved into production because of problems with high operation voltage and slow capacitor charging time.
The researchers report how combining the new liquid crystal with a performance-enhancing electrode structure can achieve light transmittance of 74% with a voltage of 15V per pixel – which could finally make field-sequential colour displays practical for product development.
"With blue-phase liquid crystals, we can use one subpixel to make all three colours, but at different times. This converts space into time, which triples the resolution density," explained Wu.
The crystal also triples the optical efficiency because the light doesn't have to pass through colour filters, which limits transmittance to about 30%. Another big advantage is that the displayed colour is more vivid because it comes directly from the red, green and blue LEDs, which eliminates colour crosstalk.
The team worked to reduce the crystal's dielectric constant to decrease 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.
"We achieved a voltage low enough to allow each pixel to be driven by a single transistor while also achieving a response time of less than 1ms," said doctoral student Haiwei Chen.
