New Paper-Thin LCD Design Could Revolutionize Printed Media

  • Engineers develop a half millimeter thick optically rewritable liquid crystal display.
  • It’s cheap to produce and consumes far less energy than conventional LCDs.
  • Flexible spacers and Polyethersulfone substrates are used to make this display.

These days, tech giants are investing a staggering amount on the development of high resolution, wide viewing angle, flexible display systems. Recently, optoelectronic engineers in Hong Kong and China came up with a new version of flexible LCD (liquid crystal display), which is half millimeter thick and tough. This futuristic display could be used as a newspaper and refreshed as fast as news cycles.

The best thing is it will cost only $5 to produce a 5 inch screen. The cost of manufacturing is low because of its simple design and structure. It only consumes energy to display text and image, just like eBook paper screen. The device doesn’t need any additional power to sustain a text and image once it’s mapped on the display.

How Did They Do It?

To build an optically rewritable liquid crystal display (ORWLCD), engineers worked on 3 key innovations.

1. Display 

Like traditional LCD, ORWLCD has a liquid crystal sandwiched between 2 plates. These plates are coated with specific molecules that restore their position/state in the presence of polarized beam, switching the pixels. However, in LCD the electric current on the plates generates enough field to change individual pixels from dark to light.

These specially-coated plates eliminates the requirement of conventional electrodes, decreases the bulk of the structure, and offers more options for thickness and type of plates.

ORWLCDs are thinner than conventional LCDs (<0.5mm thick), weighs only a few grams and they could be produced with flexible plastic.

2. Spacers 

Spacers are used to separate glass or plastic plates. They determine liquid crystal’s thickness. It’s very important to have a constant thickness to maintain decent response time, contrast ratio and viewing angle.

However, when you bend a display, the plate pushes the liquid crystal away from the impact location, leaving a portion of a screen blank. So the design of spacer needs to be improved in flexible LCDs. Fortunately, engineers have found a perfect solution for this.

Top view of systematic view of adhesive spacers

To prevent liquid crystal from flowing when screen is hit or bend, the spacer needs to be structured like a mesh. They designed a stamp to create a mash of adhesive spacers, and used a finite component analysis program to simulate the spacers’ bending.

Reference: Applied Physics Letters | doi:10.1063/1.5021619

3. Enhanced Color Rendering 

Flexible blue ORWLCD | Zhang et al.

Until this breakthrough, ORWLCDs had capable of displaying two colors simultaneously. Now, it can display three primary colors at the same time. Engineers have done this by putting a unique liquid crystal behind the display, which reflects red, green and blue light.

More specifically, they combined a fabricating flexible cholesteric liquid crystal and flexible optically rewritable ePaper. To modulate the light intensity locally, they formed a pattern of reflected colors on the equipment, using a mask comprised of sequence of semi-transparent pixels.

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However, to turn this equipment into a commercial device, they need to further improve the display’s resolution. Also, to make it compatible with full color, they need to reduce the size of the pixel for human eyes to see.

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