General Description of the Technology
Electronic paper is a computerized paper-like display. There are two main components to this product: the display portion which contains electronic ink and the backplane to the ink or e-paper. E-paper can either be rigid, similar to an LCD screen, or flexible. Advantages of e-paper include the readability of printed material as well as the refreshability of an electronic display (Adams 18). Additional advantages and disadvantages will be further described throughout these posts as well as listed in Table 1 of the Appendix at the end of this post. Recent advances in new material and manufacturing techniques have lowered e-paper’s voltage requirements, thus making it more commercially viable for a variety of applications. Unlike a computer, e-paper has high legibility which makes it easy to display complex information. Anyone who has used a computer for an extended period of time knows that the screen gets harder and harder to read. In this respect, users of e-paper describe the product as more like paper than a computer and the actual texture of the display is said to “feel almost like a paperback” (Farell 1). These aspects appeal to users who enjoy holding their reading material. However, it is also important to note that many readers consider this product “hardly (a) must have gadget” (Farell 1).
Electronic ink is produced using two different technologies. The first technology is based on the principles of electrophoresis. Electrophoresis was first observed by Reuss in 1807. He observed that when clay particles are dispersed in a fluid and a charge is applied to that fluid, the electrically charged particles will migrate depending on the type of charge applied (Adams 19). Imagine two magnets: one is positively charged and the other is negatively charged. As the old adage goes, opposites attract. If the magnets had the same charge, they would repel each other. The only difference with electrophoresis is the magnets are suspended in an electrically conducive fluid so that when a charge is introduced the magnets will either attract or repel each other.
In the case of electronic ink, the process is virtually the same except the particles are millions of tiny microcapsules about the diameter of a human hair and the fluid that these microcapsules are suspended in is a medium that is advantageous to existing screen printing processes. Using this combination of technologies, almost anything can be printed on including glass, plastic, fabric, and paper. Previously, one of the largest hurdles for e-ink’s commercialization was the voltage requirement needed to move the particles. This voltage was in the hundreds of volts which impeded e-paper’s progress.
There are two main companies that use electrophoretic technology. The first is E Ink. E Ink uses a two particle system that contains white and black microcapsules suspended in a clear fluid. When a negative field is applied, the white capsules move to the top while the positive charge pulls the black down. Through this method E Ink is able to produce images and words in grayscale (Adams 21). Sipix, on the other hand, uses a single particle method. The white particles are suspended in a dielectric fluid within a matrix called microcups. Microcups contain a variety of colors (one color per microcup). When the electric field is applied, the particles migrate through the dielectric fluid. If the particles are at the surface, the user will see white. However, if the particles are not at the surface, color will be seen. Currently, only monochromatic colors (i.e. white/black, white/red, etc.) are possible. Sipix is currently working on white/black/red and other RGB combinations (Adams 21).
The second type of technology used to produce electronic ink is called BiNem. Nemoptic utilizes BiNem technology. This is a variation of the conventional LCD technology which uses transistors. BiNem is based on “surface anchoring breaking” which is patented by Nemoptic (Nemoptic). Simple pulses are applied which causes one of two possible states to occur, the twisted or the uniform state. This is described as bistable. Once the image appears or a state occurs, it is capable of lasting indefinitely without using any more power (Nemoptic).
This next section describes the second component that makes up e-paper, the backplane. The backplane, as the name implies, goes behind the image. There are several different types of backplanes. The first type of backplane technology uses a printed circuit board (PCB). The PCB is able to mechanically support and connect electronic pathways (PCB Design). This does not use transistors to power the e-ink technology as described above with Nemoptic’s process for changing states. Instead, an internal control monitors and supplies a charge to each segment of the device (PCB Design). The PCB technology can either be rigid or flexible. The rigid or segmented version is on the market and is used in applications that require a hard backing (Adams 23). One use for a rigid backplane is a watch. A flexible version, on the other hand, is nearing commercialization. This will most likely be made up of a plastic substrate that is bendable.
The second type of backplane uses an active matrix. This technology is currently used in e-books. This technology utilizes traditional glass based thin-film transistors that rely on an electrical field to control the shape and conductivity of a charge (Thin Film Transistor Technologies). Each dot or pixel within the image is controlled by its own transistor. This technology is very thin and is currently being developed to be flexible. Flexible backplanes are also being experimented with using polymer transistors (Adams 23).
Competitor Analysis
The main groups of competitors include the manufacturers of LCDs, those in the printing industry, and other developers of e-paper. The future of LCD products includes flexible LCD panels using a plastic substrate that can bend and flex. It is specially designed for mobile uses. System designers and other equipment manufactures may also apply flexible LCD technology to areas such as fashion-enhancing or wearable electronic display designs (Lucas). These new types of LCD screens share some of the features of electrophoretic e-paper. As different technologies converge on a similar end product – thin flexible displays capable of displaying different types of media, it remains to be seen which format will ultimately win out.
As mentioned before, the major players in the e-paper field are E Ink, Sipix and Nemoptic. As described above, E Ink uses eletcrophoretic technology. Its e-paper product is known as Viplex imaging film. It is available in a range of display sizes (Adams 20). The main products that use E Ink’s technology include the Sony e-reader, Lexar jump drive, broadsheet prototype kit, iRex iLiad e-book and large area signs (E Ink Corporation). The technology is also being used to develop products by Prime View International, Samsung, Epson and LG Display. Polymer vision, while using E Ink’s technology, is currently working on a rollable display device. This is being developed for use in cell phones such as the Readius (Adams 20).
Sipix also uses electrophoretic technology. Sipix started with smart cards and shelf displays. They are now developing high-resolution displays and consumer devices such as clocks, watches and board games (Adams 20). Its website highlights six main product categories, high resolution displays, electronic shelf displays, information displays, consumer products, indicators and icons, and smart cards (Welcome to Sipix: the electronic paper leader). Within each of these categories are a variety of applications.
The final company is Nemoptic which uses the BiNem technology, a variant of LCD technology. Seiko is capable of producing a high volume of Nemoptic’s product at a low cost. It primarily focuses on its use for electronic shelf labels, point of purchase systems, home automation, and handheld devices such as e-books, smart cards and mobile phones (Adams 20). Nemoptic’s web-site highlights three main products which mainly focus on shelf labels and point of purchase devices (Nemoptic).
There are six main points of parity to be made between this new technology and other competing technologies. These factors are sticking points for the overall adoption of e-paper. The comparison points include the contrast ratio, the reflectance, the resolution, and the rate of refreshing.
The contrast ratio refers to the whiteness of the white versus the blackness of the black. The electrophoretic systems (i.e. E Ink and Sipix) have a contrast ratio of 6:1 to 20:1. This compares to a newspaper which is 4:1 to 5:1. Wristwatches are usually about 3:1. On a reflective display it is hard to distinguish the contrast ratio, but it is usually about 10:1 (Adams 22). It is desirable to have a higher contrast ratio because it allows more distinction and a sharper line between the blacks and whites. The technology behind e-paper is very competitive with the competing technologies.
Reflectance refers to how much light is reflected back from the display. To measure this, a light is focused on the surface and then the amount that bounces back is measured. A very white sheet of paper will have a reflectance in the range of 80-95 per cent. A reflectance above 30 per cent is not noticeable unless compared side to side (Adams 22). In other words, an object with a reflectance of 45 per cent is indistinguishable from one with 30 per cent unless the two objects are next to each other. The difference in reflectance is most noticeable when viewing the surface from different angles. E-paper technologies have very good reflectance. This is because their reflectiveness is different than that of a mirror. A mirror bounces light right back to the viewer. This is what LCD technology does. With e-paper, the surface is isotropic. This means that when light hits it, the light is scattered (Adams 23). Because of this the image looks the same no matter what angle it is viewed at and the image will always have the same brightness. This may be e-paper’s biggest advantage. Sipix and Nemoptics boast reflectance of 30 per cent. E Ink is slightly better at 40 per cent (Adams 23). While the specific numbers have not been cited, it is known that e-paper’s reflectivity is six times that of an LCD (“Paper-like Display…”). Reflectance does not need to be improved.
Resolution is the third point of parity. It is based on the crispness between dark and light. The backplane technology places the biggest limitation on resolution because the higher the resolution of the backplane, the higher the resolution of the image that can be created. For traditional print material such as magazines, an image resolution of less than 300 dpi is not recommended because of lowered image quality. Ideally, if color images are to be used, they should be at least 350 dpi. Nemoptic has a resolution of 150 dpi, E Ink is 397 dpi and Sipix has yet to be measured (Adams 23).
The fourth point concerns the rate of refreshing. Currently, this is the biggest disadvantage of the technology and limits the markets for commercialization. LCDs can refresh every 8 milliseconds. E Ink’s products are able to refresh every 1,000 milliseconds. Obviously, there is a huge difference between these two products if current e-paper companies were to try and compete in the same markets as LCDs. Fortunately, the next generation of e-paper technology will refresh at twice the rate (i.e. every 500 milliseconds) (Adams 19).
Fifth, e-paper also has what is known as high comparison (“Paper-like Display…”). This point is relevant mainly between LCD technologies. Comparison refers to the quality of the display based on external environmental rays. The higher the comparison, the stronger the environmental rays can be on the product for it to still be useful. E-paper’s high comparison rate makes it great for outdoor use. LCD technology does not allow for this because it would be too difficult to view the display. The comparison of e-paper is double that of LCD and newspaper. LCDs have low comparison because backlighting is necessary to view images on the screen.
The final and sixth point of parity regards the thickness between LCDs and e-paper. E-paper can be as thin as 0.5 mm while LCD is around 2 mm. E-paper is also much cheaper than an LCD to produce. LCDs require the use of an expensive back light module. An LCD screen is also fragile and requires strict packaging techniques (“Paper-like Display…”). There is no threat of theft with e-paper because the product is useless if stolen. LCD screens, on the other hand, are expensive and can be used for alternative uses if stolen. Finally, it is possible to stare at e-paper for extended periods of time. This is not possible with LCD screens. Refer to Table 2 for a condensed listing of these comparison points.
In my final post about the commercialization of e-paper, I will discuss complementary technologies, strategies for commercialization, and funding requirements and sources. Following this discussion about e-paper, I will turn to a case study that my team and I developed over a six month period. We analyzed the newspaper industry’s business model in order to develop strategies to combat the decline of circulation and advertising revenues. In these posts, I will detail our research and conclusions.
Appendix
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Table 1: Advantages & Disadvantages of e-paper |
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Advantages |
Disadvantages |
|
Readability |
Inability to display Video |
|
View at any angle |
Color display |
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Reflects light like normal paper |
No backlight |
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Read in ambient light |
Price barriers |
|
Bistable |
|
|
Variety of backplanes (i.e. flexible) |
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|
|
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Table 2: Comparison between e-paper and competing technologies |
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Technology |
Contrast Ratio |
Reflectance |
Resolution |
Rate of Refreshing |
Comparison |
Thickness |
|
|
Electrophoretic e-paper |
6:1 – 20:1 |
>30% |
397 dpi |
1,000 milliseconds |
2x |
0.5 mm |
|
|
BiNem e-paper |
n/a |
>30% |
150 dpi |
n/a |
2x |
0.5mm |
|
|
Newspaper |
4:1 – 5:1 |
>30% |
n/a |
n/a |
2x |
n/a |
|
|
LCD |
~10:1 |
>30% |
1080 dpi |
8 milliseconds |
2x |
2mm |
|
Works Cited
Adams, Larry. “Electronic Paper.” Appliance Design. May 2008. 4 Nov. 2008. www.appliancedesign.com.
E Ink Corporation. October 21, 2008. http://www.eink.com/
Farell, Maureen. “Is E Ink Publishing’s Savior?” Forbes. 8 Aug. 2008. 4 Nov. 2008. http://www.forbes.com/entrepreneurs/forbes/2008/0915/060.html
Lucas, John. “Samsung Electronics Develops Largets Flexible LCD Panel.” Business Wire. 28 Nov. 2008. 29 Nov. 2008. http://www.businesswire.com/portal/site/google/index.jsp?ndmViewId=news_view&newsId=20051127005040&newsLang=en
Nemoptic. November 10, 2008. http://www.nemoptic.com/
“Paper-like Display Industry Report, 2007 (Chinese Version).” ResearchAndMarkets. June 2007. 2 Nov. 2008. http://www.researchandmarkets.com/reports/497715/paper_like_display_industry_report_2007
PCB Design. November 24, 2008. http://www.smps.us/pcb-design.html
Thin Film Transistor Technologies. November 24, 2008. http://www.eecs.berkeley.edu/~tking/tft.html
Welcome to Sipix: the electronic paper leader. November 24, 2008. http://www.sipix.com/
Co-Authors: Adam G., Jeff B., Chris W.
