Appliance Design - May 2008 - (Page 23)

DISPLAYS & INDICATORS A clock that uses SiPix’s e-paper. a predictable angle. In this case, the surface luminance is isotropic and operates under the Lambertian reflectance principle in which light falling on the surface is scattered and the apparent brightness of the surface is consistent to an observer no matter what is the observer’s angle of view. SiPix tends to be about 30 percent reflectance as does Nemoptic’s LCD technology. E Ink is around 40 percent. Backplanes too have been improved. For the most part, an e-paper display – the front, visible plane of the display -- is “agnostic,” says Chan, and can be used in a variety of backplanes. Often, flexible and segmented displays use a printed circuit board (PCB) backplane while active matrix applications such as the E-books use a backplane made from traditional glassbased thin-film transistor (TFT) technology. According to Chan, backplanes can come on a variety of substrates including glass, plastic, or metal. The technology that drives each pixel also varies. For active matrix displays, where an image is made from individual pixels, each dot (or pixel) needs a transistor, he says. The flexible active matrix displays are nearing commercialization and will likely be made of a plastic substrate. The transistor is also flexible because they are very thin. Another form of flexible transistors are polymer transistors. Unlike TFTs, these can also be printed. For segmented displays, such as a clock or watch, the image is created by a conductive electrode (either copper or silver) that is on a PCB. Since flexible PCBs have been around for some time, this technology is already available and on the market. Flexible direct drive backplanes don’t have any transistors on them. Instead, the electrodes are given a charge from a display driver IC that controls the voltage on each segment, Chan says. The primary advantage with flexible displays is that there is no glass to shatter, says Peruvemba. Therefore it is easier to design them into applications like wearable computers, handheld devices, military equipment, clothing, restaurant menus or even ladies hand bags that was not possible with a rectangular glass based display, he says. A flexible display affords an advantage even in applications where it won’t actually be flexed in that it provides a greater degree of impact resistance. A flat, flexible polymer display can withstand an impact that might break a display with glass. Resolution is another measuring stick for e-paper products. This determines how crisp is the line between the dark and the light. As for resolution, the limitation is in the backplane. The higher the resolution of the backplane, the higher the resolution image can be created. Nemoptic’s resolution is about 150 dpi, and E Ink has demonstrated a resolution of 397 dpi. SiPix has not measured the resolution of its electrophoretic material. The suppliers say that new and more flexible active matrix backplanes are in the pipeline and might be available as early as this year or next, which might help in developing further applications. With these past and future developments, e-paper may be an option for designers of a range of appliances, large and small, that require a tough, low-paper product that is easy to read and easy to use. < For more information, enter E Ink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301 Or email: sales@eink .com Nemoptic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .302 Or email: contact@nemoptic .com SiPix Imaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .303 Or email: bryan .chan@sipix .com A SiPix Microcup contains white particles in a dyed liquid, and various colors can be used. The white particles move to top or bottom in response to a positive or negative charge. With the particles at the top, the pixel is white. With the particles at the bottom, the pixel is the color of the dyed fluid. www.applianceDESIGN.com applianceDESIGN May 2008 23 http://www.appliancedesign.com

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Appliance Design - May 2008 Contents Editorial Shipments/Forecasts News Watch New and Notable Displays & Indicators Elastomers Quality & Standards Indoor Air Quality IHHS Highlights New Products Classifieds Design Marts Advertiser’s Index Association Report: PSMA

Appliance Design - May 2008

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