Research Brief Digital Paper's Developers Bet on a Bright, Clear Future Abstract: Digital paper offers the promise of flexible, low-power, high-contrast displays. But as the technology edges toward commercialization, potential users will want to see better color handling, resolution and refresh rates. By Jim Tully and Rafe Ball Strategic Market Statements Digital paper has two limiting factors: uncertain color handling and poor moving-image capabilities. The technology will be used first in niche devices with low refresh rates like e-book readers. These devices will emerge during the next two years. Digital paper technology will not see significant use in mobile devices until refresh rates and display quality improves. Such improvements will not happen until at least 2005. Retail point-of-sale displays using digital paper technology are already being tested. But they are unlikely to be adopted commercially in any significant numbers before 2005. Recommendations Digital paper displays offer a low-power solution for devices with low screen-refresh needs; manufacturers of such devices should evaluate this technology. Device manufacturers requiring support for fast-moving images such as video should wait for improvements in refresh rates before considering adoption. Digital paper displays for signage present significant potential benefits; retailers in particular should consider this technology as it becomes more widely available. Publication Date:28 April 2003
2 Digital Paper's Developers Bet on a Bright, Clear Future What Is Digital Paper? Figure 1 Passive vs. Active Digital Paper Digital paper, also referred to as digital ink, electronic paper or electronic ink, is a technology intended to produce a display that is similar to paper in many ways. It resembles a sheet of plastic-laminated paper. Beneath the plastic are tiny microscopic beads that change color to form text and images. The result is a nearly paper-thin, rewritable display. Digital paper comes in two forms: active and passive (see Figure 1). In passive form, an external device like a wand or a specially designed printer head supplies the electrical charge needed to change bead color. The active form is used when digital paper is needed for a device display. In this case, a backpane of electrodes is laid behind the digital paper, allowing the image to be updated as desired. Passive Digital Paper Active Digital Paper Viewing Direction Viewing Direction Thin plastic sheet Thin plastic sheet External device (for example, a wand) to change particles No power requirement Internal electrodes charge particles Very low power requirement 114248-00-01 Source: Gartner Dataquest (April 2003) Reasons for Using Digital Paper Low power requirement: The display is bistable; once it has been "set" by applying current, the digital paper maintains the image even when the power is turned off. Power is needed only to update the display. Wide viewing angle: Unlike many traditional display types, digital paper can be viewed from any angle. LCDs have a much narrower viewing angle. High contrast: The contrast ratio for digital paper is more than twice that of traditional LCDs. It also has a much greater brightness. This makes viewing easier even in low-light conditions display illumination is needed less often, resulting in further power savings. Digital paper displays do not "wash out" in bright light, which is a problem with LCDs. Form: Digital paper is light, thin and flexible (though this depends partly on the backpane to which it is attached). Therefore, it can potentially be used where it is unsuitable to use traditional displays (for example, smart cards) and to reduce the weight of devices using traditional screens.
3 But Beware of Challenges Resolution: Digital paper technology offers resolution of about 100 dots per inch. While this is close to the resolution of LCDs used in personal digital assistants (PDAs), it is somewhat below that of higher-range thin film transistor (TFT) screens and far behind paper printouts produced by even relatively inexpensive inkjet printers. Refresh rate: Digital paper has a far lower refresh rate than that of LCDs, making it unsuitable for fast-moving images such as video. Color: Digital paper is largely limited to two-color output, though multicolor output is being researched and developed. Two Major Digital Paper Manufacturers Figure2 E Ink Electronic Ink EInk E Ink's proprietary electronic ink utilizes tiny capsules about the diameter of a human hair. Each capsule contains positively charged particles of one color and negatively charged particles of another. These particles are suspended in a clear fluid. The electronic ink is then printed on a sheet of plastic film laminated to a layer of circuitry. When a charge is applied, it draws the oppositely charged particles toward it. By reversing the charge, the apparent color of the capsule changes (see Figure 2). Positively charged white chips Clear fluid Negatively charged black chips + + + Top (transparent) electrode Bottom electrode 114248-00-02 Source: E Ink E Ink has used its technology in signage-type applications, involving low-to-midsize segment counts applications that often use light-emitting diode (LED) displays, like signage for public transport information and retail point-of-sale signage. (A segment is an individually changeable piece that can be "on" or "off"; for example,adigitalwatchwouldhavealowsegmentcount;anintendogameboy display would have a very high segment count). E Ink has also used it in active matrix displays for devices like PDAs and mobile phones.
4 Digital Paper's Developers Bet on a Bright, Clear Future Figure 3 Gyricon Media SmartPaper E Ink has shifted its focus to the application of digital paper technology for device displays. E Ink's goal is to produce RadioPaper, a display with readability equal to normal type on paper, on to which newspapers, novels and so on could be downloaded when desired. Though electronic ink technology has been limited to two-color (bichromal) displays, E Ink has now produced a prototype color display in partnership with Royal Philips Electronics and Toppan Printing. The 5-inch (13-cm) prototype screen is capable of displaying 4,096 colors at 80 pixels per inch (ppi). E Ink plans to release this technology commercially in 2004. This partnership aims to have simpler monochrome displays for handheld devices available during 2003, having already demonstrated displays with resolutions close to 100 ppi. Gyricon Media Gyricon Media is a spinoff from the Xerox Corporation. Its SmartPaper works slightly differently to E Ink's electronic ink, but has a similar resolution. Though it uses particles of about the same size as those used in electronic ink, these are small bichromal beads. Each bead has one hemisphere of one color and one of another. The hemispheres are also of opposite charge. SmartPaper consists of two thin plastic sheets with millions of these particles sandwiched between. When an electric charge is applied, the beads to rotate according to the polarity of the charge, thus determining which color is displayed (see Figure 3). SmartPaper is therefore limited to two-color displays. Viewing Direction Thin plastic sheet + + + + + 114248-00-03 Source: Gyricon Media Gyricon realizes the technology's potential for device displays, but is focusing on applications in retail signage. Its MaestroSign system uses SmartPaper for retail point-of-sale signs to display pricing and other product information that can be updated via a wireless network. The signs can reflect real-time changes in price, rotate between different "special offer" details and so on. Because of savings on space, printing costs and resources involved in manually changing paper displays, this application could be particularly attractive to retailers. Real-time pricing
5 updates would also reduce the chances of "mispricing." This would help avoid customer dissatisfaction where the displayed price is too low or loss of potential custom where it is too high. And it would help retailers avoid fines for inaccurate pricing. Gyricon has undergone pilot programs with Dow Jones and Macys East. Further pilots are planned for this year. Gartner Dataquest Perspective Compared with other emerging flexible display technologies such as organic LEDs (OLEDs) and light-emitting polymers (LEPs), digital paper has one inherent advantage: nonvolatility of the image. In other words, the image remains after power is switched off. But there are two main disadvantages: uncertain color handling and poor movingimage capabilities. This will restrict the technology to "paper replacement" applications and to relatively static displays, potentially of large size. An inability to handle moving images eliminates most of the mainstream display applications in the consumer, data processing and communications fields. Even mobile phone displays are starting to be used for playing videos. Until the refresh rate can be improved, this technology is best suited to devices where the display does not need to incorporate moving images, such as e-book readers. Smart cards, packaging and labeling, including barcodes, are other interesting potential applications for the technology. Digital paper technology presents a potential display solution with several benefits over LCD technologies, especially for today's power-hungry mobile devices. Both E Ink and Gyricon are hesitant to reveal details of cost, but they are aiming to produce displays at a lower cost than traditional LCDs. Trials of retail point-of-sale displays are already in place, with more planned for 2004. But retailers are unlikely to adopt this technology in any significant numbers before 2005. This is mainly owing to the technology's limitations regarding color and the depiction of movement. Regarding the use of this technology for device displays, digital paper could become a viable alternative for manufacturers producing devices with low screen-refresh requirements within the next two years. A small number of niche devices using digital paper will emerge in the same period, for example, e-book readers. For mobile devices, such as PDAs and high-end multifunction phones, this technology is unlikely to beat traditional LCDs and upcoming alternatives like OLEDs and LEPs until refresh rates and display quality improves. Such improvements will not happen until at least 2005. Key Issue What impact will emerging chip technology have on system trends?
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