Progress Reported in Video Rate Electronic Paper Technology

At Display Week 2018, a team led by Professor Guofu Zhou of the Electronic Paper Display Institute within the South China Academy of Advanced Optoelectronics at the South China Normal University (Guangzhou, China) demonstrated their latest technical achievements and prototype devices in the field of color, video rate electronic paper displays.

Last year, the team reported a unique spacer technology suitable for electrofluidic, electrowetting e-paper displays. The approach was reported as providing needed robustness to such displays making them more resistant to external mechanical pressure.

Since last year, the team has optimized the dye formula and modified the pixel structure used in the prototype displays. By these means, the resulting color displays can now present a gamut of more than 50% NTSC. In addition, the pixel aperture of the displays has been increased to more than 80% and the contrast ratio to over 10:1. Both color and monochrome displays are brighter offering up to a reflectance of 50%.

The turn on and turn off response times of the displays have also been improved and are now below 3 ms, rivaling that of an LCD. As a result, a prototype monochrome device was able to show a video running at up to 100 frames per second. Such a frame rate is represented as a big step forward in electronic paper technology.

Significant progress was also reported towards operating the display at voltages similar to a LCD. At a power level of about 100 nW/cm², the electronic paper displays consume significantly less power than an equivalent sized LCD.

Using a prototype 2.7″ electronic paper display, the team demonstrates a clock. Reportedly, the clock could work for years with a single coin battery. The team also exhibited two other new prototypes: one is a segmented color signage board and the other is an “ultra-bright” monochrome billboard. The figure below illustrates several of the prototypes shown during Display Week 2018.

A collection of single and multicolor electronic paper display prototypes. Also in the figure are vials containing colored dyes.

During the past year, the Electronic Paper Display Institute team announced a collaboration with industrial partners as part of the process of commercializing their display technologies. These partners are identified as Shenzhen Guohua Optoelectronics Ltd. and GR8 Optoelectronics Ltd. (Hong Kong).

The team expects to be able to finalize device development during the next few months. The goal is to start shipping sample electronic paper displays to interested customers some time during this summer. More than that, Alex Henzen, technical leader of the electronic paper team, stated that the collaboration is moving towards device fabrication using a new Gen 2.5 prototype line. The line is designed with the capability to produce substrates having a size of 400 x 500 mm at a rate of 30,000 per month. -Arthur Berman