Tag Archives: electronic paper

Brilliant colours in electronic paper displays

Researchers at Chalmers University of Technology (Sweden) have taken a step forward towards making science fiction writers’ fantasies of reading paper-like electronic displays outdoors under the sun reality with a new technique that results in more brilliant colour displays.

Caption: A new design from Chalmers University of Technology could help produce e-readers, advertising signs and other digital screens with optimal colour display and minimal energy consumption Credit: Image:, Marika Gugole/Chalmers University of Technology

From a July 12, 2021 Chalmers University of Technology press release (also on EurekAlert and received via email),

Imagine sitting out in the sun, reading a digital screen as thin as paper, but seeing the same image quality as if you were indoors. Thanks to research from Chalmers University of Technology, Sweden, it could soon be a reality. A new type of reflective screen – sometimes described as ‘electronic paper’ – offers optimal colour display, while using ambient light to keep energy consumption to a minimum.
Traditional digital screens use a backlight to illuminate the text or images displayed upon them. This is fine indoors, but we’ve all experienced the difficulties of viewing such screens in bright sunshine. Reflective screens, however, attempt to use the ambient light, mimicking the way our eyes respond to natural paper.
“For reflective screens to compete with the energy-intensive digital screens that we use today, images and colours must be reproduced with the same high quality. That will be the real breakthrough. Our research now shows how the technology can be optimised, making it attractive for commercial use,” says Marika Gugole, Doctoral Student at the Department of Chemistry and Chemical Engineering at Chalmers University of Technology.
The researchers had already previously succeeded in developing an ultra-thin, flexible material that reproduces all the colours an LED screen can display, while requiring only a tenth of the energy that a standard tablet consumes. But in the earlier design the colours on the reflective screen did not display with optimal quality. Now the new study, published in the journal Nano Letters takes the material one step further. Using a previously researched, porous and nanostructured material, containing tungsten trioxide, gold and platinum, they tried a new tactic – inverting the design in such a way as to allow the colours to appear much more accurately on the screen.
Inverting the design for top quality colour
The inversion of the design represents a great step forward. They placed the component which makes the material electrically conductive underneath the pixelated nanostructure that reproduces the colours – instead of above it, as was previously the case. This new design means you look directly at the pixelated surface, therefore seeing the colours much more clearly.
In addition to the minimal energy consumption, reflective screens have other advantages. For example, they are much less tiring for the eyes compared to looking at a regular screen.
To make these reflective screens, certain rare metals are required – such as the gold and platinum – but because the final product is so thin, the amounts needed are very small. The researchers have high hopes that eventually, it will be possible to significantly reduce the quantities needed for production.
“Our main goal when developing these reflective screens, or ‘electronic paper’ as it is sometimes termed, is to find sustainable, energy-saving solutions. And in this case, energy consumption is almost zero because we simply use the ambient light of the surroundings,” explains research leader Andreas Dahlin, Professor at the Department of Chemistry and Chemical Engineering at Chalmers.
Flexible with a wide range of uses
Reflective screens are already available in some tablets today, but they only display the colours black and white well, which limits their use.
“A large industrial player with the right technical competence could, in principle, start developing a product with the new technology within a couple of months,” says Andreas Dahlin, who envisions a number of further applications. In addition to smart phones and tablets, it could also be useful for outdoor advertising, offering energy and resource savings compared with both printed posters or moving digital screens.
More about the research
• Research on the nano-thin electronic paper has been ongoing for several years at Chalmers, and the work has been rewarded with both international attention and major strategic research grants.
• The technology in Chalmers researchers’ reflective screens is based on the material’s ability to regulate how light is absorbed and reflected. In the current study, tungsten trioxide is the core material, but in previous studies, researchers also used polymers. The material that covers the surface conducts electronic signals throughout the screen and can be patterned to create high-resolution images.
• The scientific article Electrochromic Inorganic Nanostructures with High Chromaticity and Superior Brightness has been published in Nano Letters and is written by Marika Gugole, Oliver Olsson, Stefano Rossi, Magnus P. Jonsson and Andreas Dahlin. The researchers are active at Chalmers University of Technology and Linköping University, Sweden.

Since the title and list of authors is included just above in a format almost identical to my usual ‘citation’, I’ll add only some publication details,

This paper appears to be open access.

Colours in bendable electronic paper

Peacocks and their structural colour inspire better resolution in e-readers

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Thank goodness birds, insects, and other denizens of the natural world have not taken to filing patents otherwise we’d be having some serious problems in the courts as I have hinted in previous postings including this March 29, 2012 posting titled, Butterflies give and give … .

This time, it’s the peacock which is sharing its intellectual property as per this Feb. 5, 2013 news item on ScienceDaily,

Now, researchers at the University of Michigan have found a way to lock in so-called structural color, which is made with texture rather than chemicals. A paper on the work is published online in the current edition of the Nature journal Scientific Reports.

In a peacock’s mother-of-pearl tail, precisely arranged hairline grooves reflect light of certain wavelengths. That’s why the resulting colors appear different depending on the movement of the animal or the observer. Imitating this system—minus the rainbow effect—has been a leading approach to developing next-generation reflective displays.

The University of Michigan Feb. 5, 2013 news release, which originated the news item, provides information about potential applications and more details about the science,

The new U-M research could lead to advanced color e-books and electronic paper, as well as other color reflective screens that don’t need their own light to be readable. Reflective displays consume much less power than their backlit cousins in laptops, tablet computers, smartphones and TVs. The technology could also enable leaps in data storage and cryptography. Documents could be marked invisibly to prevent counterfeiting.

Led by Jay Guo, professor of electrical engineering and computer science, the researchers harnessed the ability of light to funnel into nanoscale metallic grooves and get trapped inside. With this approach, they found the reflected hues stay true regardless of the viewer’s angle.

“That’s the magic part of the work,” Guo said. “Light is funneled into the nanocavity, whose width is much, much smaller than the wavelength of the light. And that’s how we can achieve color with resolution beyond the diffraction limit. Also counterintuitive is that longer wavelength light gets trapped in narrower grooves.”

The diffraction limit was long thought to be the smallest point you could focus a beam of light to. Others have broken the limit as well, but the U-M team did so with a simpler technique that also produces stable and relatively easy-to-make color, Guo said.

“Each individual groove—much smaller than the light wavelength—is sufficient to do this function. In a sense, only the green light can fit into the nanogroove of a certain size,” Guo said.

The U-M team determined what size slit would catch what color light. Within the framework of the print industry standard cyan, magenta and yellow color model, the team found that at groove depths of 170 nanometers and spacing of 180 nanometers, a slit 40 nanometers wide can trap red light and reflect a cyan color. A slit 60 nanometers wide can trap green and make magenta. And one 90 nanometers wide traps blue and produces yellow. The visible spectrum spans from about 400 nanometers for violet to 700 nanometers for red.

“With this reflective color, you could view the display in sunlight. It’s very similar to color print,” Guo said.

Particularly interesting (for someone who worked in the graphic arts/printing industry as I did) are the base colours being used to create all the other colours,

To make color on white paper, (which is also a reflective surface), printers arrange pixels of cyan, magenta and yellow in such a way that they appear to our eyes as the colors of the spectrum. [emphasis mine] A display that utilized Guo’s approach would work in a similar way.

To demonstrate their device, the researchers etched nanoscale grooves in a plate of glass with the technique commonly used to make integrated circuits, or computer chips. Then they coated the grooved glass plate with a thin layer of silver. When light—which is a combination of electric and magnetic field components—hits the grooved surface, its electric component creates what’s called a polarization charge at the metal slit surface, boosting the local electric field near the slit. That electric field pulls a particular wavelength of light in.

The base colours in printing are CMYK (cyan, magenta, yellow, black). At least, that was the case when I worked in the graphic arts industry and quick search on the web suggests that standard still holds.(Have I missed a refinement?) In any event, here’s an image that demonstrates how this new colour scale can be used,

University of Michigan researchers created the color in these tiny Olympic rings using precisely-sized nanoscale slits in a glass plate coated with silver. Each ring is about 20 microns, smaller than the width of a human hair. They can produce different colors with different widths of the slits. Yellow is produced with slits that are each 90 nanometers wide. The technique takes advantage of a phenomenon called light funneling that can catch and trap particular wavelengths of light, and it could lead to reflective display screens with colors that stay true regardless of the viewer’s angle. Image credit: Jay Guo, College of Engineering

You can find more about this work in the ScienceDaily news item, which includes a link to the abstract, or in the University of Michigan news release, which includes more images from the scientists.

Pebble’s e-paper watch wins over $3M in funding through crowdfunding

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I gather it’s the most successful crowdfunding project Kickstarter has hosted yet. The Pebble team asked for $100,000 to realize their e-paper/ smartwatch project and have raised over $3M while they still have 30 days left in their campaign. In the kind of twist that makes one smirk, they posted the project on Kickstarter as they were unable to raise sufficient funds in Silicon Valley. From the April 16, 2012 Q&A with Alexandra Chung at Wired,

Wired: Are you surprised by the reception to Pebble? What were you hoping for when you launched on Kickstarter?

Migicovsky [Eric Migicovsky, Pebble founder and lead designer]: We were expecting $100,000 over a month, so when it came in two hours, it was a surprise. On Thursday, we were earning $80,000 an hour. By Sunday morning, we passed the Wasteland 2, which was the second most popular Kickstarter after Double Fine Adventures.

…

Wired: Has the influx of funding affected your production plans? Are you changing your strategy at all?

Migicovsky: We’re basically leveling up. We had a variety of paths we could have followed. We were originally aiming for $100,000, so we had a production path that we could have followed to meet that $100,000. Now we’re following a path that is several levels higher than that.

Right now, we don’t have any specifics for where the product is being made. There are various levels of contract manufacturers, and we’re going to use a contract manufacturer. We’re moving to a one-stop shop, so we come with X amount of orders.

On the one hand, six months is not very long to bring a product to market. But we have this huge backer community that will help us get there. They are providing the funding that’s helping us make quality decisions, like spending money now on making a more aesthetically pleasing product. We’re making those decisions now.

We had a design plan with several different levels. It’s not like we are drastically altering the design. We just had “gotta haves,” like 7-day battery life, and then the “nice to haves” like more water-resistance, which are the features we’re moving into now.

Here’s a description of the pr0ject and the product from the April 17, 2012 news item on the BBC News website,

The Pebble watch reached the $1m mark in 28 hours. The firm behind the device, which has been designing smartwatches for three years, said that it was “blown away” by the support.

The watch has an electronic paper screen and connects via Bluetooth with iPhones or Android powered devices to allow users to customise the watch face and download apps.

The display stays on at all times and is backlit for night viewing. The firm says that the rechargeable battery will last a week.

It can display distance and speed for runners and cyclists, control a smartphone’s music, and show emails, messages and reminders.

The watch will go head to head with an Android-compatible device released in April by electronic giant Sony Corp. The Sony Smartwatch costs $149.99.

This video should answer a few more questions about the watch,

Migicovsky is Canadian. Originally from Vancouver, he graduated from the University of Waterloo and made his way to California. From the April 17, 2012 article by Chuck Howitt for the Record.com,

The Pebble smartwatch is a “natural evolution” of the inPulse smartwatch that Migicovsky started working on while a student at UW [University of Waterloo] in 2008.

Released in 2009, the inPulse connected wirelessly with BlackBerry smartphones to indicate when the user had an email, message or call.

Sold through a company he called Allerta Inc., sales of the inPulse have been rather modest, about 1,500 to date, admits Migicovsky.

So the 26-year-old Vancouver native set his sights on the booming iPhone and Android markets.

To crack the California market and raise funds at the same time, he applied for admission to Y Combinator, a technology incubator based in Silicon Valley, in early 2011.

Successful applicants are guaranteed about $20,000 on admission plus more funding at the end of an intense three-month internship. Migicovsky was able to raise about $375,000 by the time he left Y Combinator, which he used to start working on the Pebble.

…

When he hit the venture capital market, he got a lukewarm response for the Pebble.

Most venture capitalists “have an aversion to hardware,” he said. “The general feeling is it costs more money. There is a little bit more risk.”

You can find out more about Pebble at the company website and, if you were wondering what SDK (as mentioned in the video) means, it’s Software Development Kit.

I recently wrote about e-paper in my April 3, 2012 posting titled,
Folding screens at University of Toronto and EPD (electronic paper display) with LG.

Electronic paper from Taiwan

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