E-paper technologies

US-based Solchroma develops a novel reflective inks and actuators based display technology, targeting the outdoor signage market (at least as a first step).

The company introduced its interesting technology at SID Displayweek 2021. The company's CEO, Dr. Roger Diebold was kind enough to explain the company's technology and business to E-Ink-Info.

Hello Roger, thank you for your time. Can you explain Solchroma's ePaper technology?

Solchroma creates reflective digital displays to change how we interact with the built environment and world around us. Solchroma’s technology is based on hydraulically forcing of colored liquid ink in and out of view. A backplane of actuators acts as an array of electrically-controlled pumps that push on nearby reservoirs of ink. Ink reservoirs are shielded from view by a white reflector, while simultaneously allowing passage of ink from the reservoirs behind the reflector to three sealed, viewable chambers stacked one atop the next on the viewable side.

TCL announced a new display technology, called NXTPAPER, which uses liquid-crystal technology on a reflective substrate, as can be seen in the image below. TCL did not disclose much about the technology, but it says it offers higher contrast compared to E Ink displays. Compared to LCDs, it offers a thinner design and also much higher power efficiency (as there's no backlighting unit).

The NXTPAPER displays offer blue-light free operation and no flicker. This is not your typical ePaper display technology, but it will be interesting to watch. TCL announced two new tablets that will sport the new display technology, at 8-inch and 10-inch sizes. It is not clear but it is likely that the tablets will include some sort of front-lighting to be visible in low light conditions.

Most people when they think about ePaper displays immediate think about E Ink. E Ink Holdings (EIH) has been very successful in bringing its ePaper displays to the market - and today these are prevalent in e-readers, electronic shelf labels, e-notebooks and many other applications. While EIH indeed has a clear leadership in the ePaper market, it is not alone.

But first of all, it is important to note that there are many display technologies that could be called ePaper displays. Most people would only consider truly bi-stable displays able to show dot-matrix images as ePaper displays, but some other technologies that are not truly bi-stable also exist and some consider these as ePaper displays as well - for example Memory LCDs. In addition some simpler displays technologies that are similar to ePaper in properties also exist. We will discuss both these technologies in this article.

Ynvisible announced a new partnership with Electrochromic Polymers developer NxtGen Nano. The two companies will work together to incorporate NXN's color Electrochromic Polymers (ECP) inks in Ynvisible's systems and manufacturing services. This will enable Ynvisible to offer a new range of color displays.

The two companies announced that they already sold a prototype multi-color project to a Fortune 500 medical and diagnostics devices company. NXN and Ynvisible have earlier experience in working together and sold several commercial color electrochromic prototype devices to several premium consumer brand product companies.

While E Ink is certainly the clear leader in the e-paper market, some companies are developing what they hope will become next-gen e-paper displays. Bodle, based in Oxford, UK, is developing a technology it calls SRD, based on research that started in Oxford University a few years ago.

SRD, or Solid-State Reflective Displays, creates color using light interference inside an ultra-thin film. The film contains a phase-change material, the same one used in writable CD-R discs. When this material is switched between its amorphous and crystalline phases, the color is changed.

E Ink developer and integrator Visionect published a new article in which the company analyses all the intricacies of deploying electronic paper in different digital signage scenarios.

The article discusses the need of a new kind of signage, the power efficiency and readability of e-paper, and the challenges in deploying e-paper signage solutions. This is a very comprehensive report, and is a good read for anyone interested in signage and in e-paper. Read it here.

China-based e-paper developer Guangzou OED Technologies announced that it developed a new graphene e-paper technology. The company aims to start producing these new screens within a year.

Graphene is the world's strongest and most conductive (to both electricity and heat) material, and it is set to revolutionize many industries - including the display industry. The company says that the new graphene-based paper is brighter and more flexible. The graphene paper is also said to have "more intensity", but I'm not sure what this means.

Oxford University researchers developed new technology based on phase-change materials (similar to ones used in re-writable DVDs) that can be used to create non-volatile highly-efficient e-paper displays. Oxford established a new company called Bodle Technologies to commercialize this new technology.

The phase-change materials can manipulate light - by electrical, optical or mechanical means - they can be used to filter, steer or dim light using very little power. Bodle already demonstrated a sub-100nm pixel size and a very rich color gamut (they say it exceeds "other display technologies"). David Fyfe (the executive chairman of Oxford Photovoltaics and the former CEO of Cambridge Display Technology) will serve as executive chairman.

Researchers from the University of Cincinnati, in collaboration with Merck and HP are developing low-cost large films that can be used to create smart windows that can dynamically adapt for brightness, color temperatures and opacity.

The so-called electro-kinetic pixel technology is based on the electrophoretic principle - the same one used in E Ink panels. The researchers are developing a way to create large-sized sheets of those pixels at low cost.

There are reports that Dutch-based EPD developer IRX Innovations has gone bankrupt. This is sad news from one of the early EPD pioneers (the original company was established over 10 years ago as Irex Technologies by ex-Philips employees).

Irex first aimed to develop e-reader based on an E Ink display. Their first e-reader (the Iliad) shipped in 2006, and they launched several more models later on. Irex Innovation went bankrupt in 2010, but it was bought by IRX Innovation which also kept all employees. Irex developed a new EPD technology which they called Electro Osmosis which is similar to E Ink (electrophoresis) but the big difference is that the liquid that contains the charged particles also move inside the pixels in Electro Osmosis (in electrophoresis only the charged particles are moving). This enables much faster refresh rates.