Electronic Paper for Digital Signage

In this article, you will learn about the different techniques behind electronic paper and which digital signage solutions and which digital signage solutions benefit from it. You will also find alternative manufacturers who develop their own panels and do not just buy from E Ink.

Kuebi = Armin Kübelbeck, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
High resolution electronic paper (Source: Wikipedia)

What is electronic paper?

Electronic paper is the name of a special screen technology that replicates some properties of normal paper. It became known through its use in e-book readers. Electronic paper does not require backlighting like LCD or LED screens, and therefore remains readable even in direct sunlight. The screens consume minimal power.

Ambiguities in the Naming

Let's also clarify some synonymously used terms that may cause confusion.

E-Paper

In English, together with ePaper or e-paper, it is simply the abbreviation of “electronic paper”. In other countries, such as Germany, different publishers reinterpreted the term. If you search for e-paper on Google.de, you will find numerous providers of electronic newspapers. The term is now used synonymously for electronic paper, electronic newspaper, electronic magazine and for electronically published scientific publications.

E-Ink

E Ink without hyphen is the brand name of an electronic paper produced by the company E Ink Corporation. It means electronic ink. This company was the first to mass produce this technology in 2004. Therefore, hyphenated E-Ink is often used as a synonym for this technology, even if they are alternatives from other companies.

Digital Paper

Digital paper or interactive paper is just ordinary paper with a grid of tiny dots printed on it. A digital pen with a built-in scanner can be used to capture handwritten notes in digital form. Some interactive games like Tipoi exist as an application of digital paper.

How does Electronic Paper work?

Electronic paper is based on electrophoresis. In this process, a short electrical voltage is applied to microscopically small capsules. These contain a transparent polymer as a carrier for white and black particles. The electricity separates the particles, which have different electrical charges. Depending on the polarization, either the white or the black particles move up and become visible to observers as a white or black dot. The state remains stable for weeks without further energy input.

Electronic paper requires a voltage only when changes are made, and is therefore considered extremely energy-efficient. This makes it possible to build lightweight devices with small rechargeable batteries. For this reason, this technology became established quickly for e-book readers. The increasingly smaller microcapsules also make it possible to display texts with greater clarity.

Bistable LCD

Another technique for electronic paper can be found in the bistable LCD from the company Kent Displays. Bistable LCD use the phase effect of certain liquid crystals. These so-called cholesteric liquid crystals have three thermotrope phases, into which they change when an electrical voltage is applied.

The homeotropic texture is translucent, while the planar texture reflects light. There still exists an unstable intermediate state called the focal conic texture. The homeotropic and planar states can be maintained without further current input. This is why it is called “bistable”.

This technique has a slower refresh rate and a limited temperature range. In return, they enable a very neutral white and resolutions of up to 200 dpi.

Principle Disadvantages of Electronic Paper

Electronic paper displays texts perfectly, but usually in monochrome. Photos therefore look less good. The long switching times caused by the technology also prevent videos or animations from being displayed smoothly. Color displays are now available, but they are cost-intensive.

What are the Advantages of Electronic Paper for Digital Signage?

The power consumption of screens based on electronic paper is minimal. With relatively inexpensive photovoltaic systems, you can operate totems stand-alone. In addition, the surfaces reflect light so well that the content is readable even in low ambient light, such as that from streetlamps. Furthermore, the content can be viewed equally well from any angle and does not flicker.

Use Cases for Digital Signage

The nature of electronic paper makes it ideal for applications where information is more important than bling-bling. For example, digital signage solutions based on electronic paper displays already exist today. In addition to saving paper, one of the biggest advantages is the possibility of digital networking.

Wayfinding and Door Signs

Electronic wayfinding signs and door signs in conference buildings, at events, train stations, airports, or trade fairs can be adjusted centrally and time-controlled. The electronic wayfinding signs make work easier in every respect and are easy to operate.

Electronic Shelf Labels

For electronic shelf labels (ESL), the above-mentioned bistable LCDs are often used because of the brighter white.

An enterprise resource planning system automatically updates price tags via interface and Wi-Fi. With a limited-time campaign, it doesn't require anyone to replace the price tags in time.

Marking up prices is time-consuming and resource-intensive. With electronic shelf labels, it requires a few minutes of time, instead of possibly several hours or even days, as with traditional price stickers. You can correct errors simply with the click of a mouse.

Timetables

Staff driving from stop to change timetables at least twice a year was yesterday. Electronic timetables in robust, vandal-proof digital totems make this unnecessary. Furthermore, you can offer your passengers additional value, such as interactive passenger information.

ŠJů, Wikimedia Commons, CC BY 4.0 <https://creativecommons.org/licenses/by/4.0>, via Wikimedia Commons
Electronic timetable in Prague (Source: Wikipedia)

Inventory, Laboratory, and Warehouse Management

Smart technologies connect the employees' tablets to the signs. This facilitates the search for stored parts and optimizes pick-by-light and put-by-light processes. Laboratory samples can be flexibly labeled and results centrally stored and displayed. Thus, these displays also effectively support smart retail concepts.

What are the Disadvantages of Electronic Paper?

Electronic paper is not suitable for displaying videos or animations. It takes too long to switch times to allow a smooth display. It requires illumination to be used in the dark. The pale appearance of the display makes it difficult to display a color display. Furthermore, these devices cost a lot right now.

Color Displays

The first generations of color displays needed almost 10s for a page load and could not display all colors. It was not until the spring of 2022 that E Ink released a panel with full color range and change times between 500 to 1500ms. However, only one e-book reader called E Ink Gallery™ Plus exists and there are no purchasable larger monitors with this technology (as of November 2022).

What Kind of Screens with Electronic Paper are there?

As the market leader, E Ink offers e-paper displays with diagonals from 1.1 inches (ca. 28 mm) to 42.0 inches (ca. 107 cm) in a resolution of up to 2160 × 2880 pixels and a color range from monochrome to 4000 colors. Various suppliers such as Holitech, Dasung, Ricoh and many others build E Ink panels into their monitor housings and sell them under their brands.

Only a few companies produce and sell e-paper panels using their own technology.

Plastic Logic (Plastic Logic), CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons
Bendable electronic paper from Plastic Logic (Source: Wikipedia)

Conclusion

In conclusion, electronic paper for digital signage is a great way to present static content. It can be centrally managed and is great for designing information. Furthermore, it is uncomplicated to use and offers a wide range of capabilities.

E-paper displays also save up to 98% of electricity costs, making their contribution to sustainable green signage.


Gravatar Nikolaos Sagiadinos
Author: Niko Sagiadinos
Developer & Co-Founder SmilControl – Digital Signage
Visit me on: LinkedIn or GitHub

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