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A cost effective light guide Disclosure Number: IPCOM000009861D
Publication Date: 2002-Sep-24
Document File: 1 page(s) / 4K

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A cost effective light guide

In displays that use dynamic light extraction from a first plate, this first plate has a dual function, it is a substrate for the switching electrodes and it is a light guide. For the latter reason, it needs to be sufficiently thick. However, glass is expensive, heavy, breakable and often shows some residual light absorption. We propose to glue a thin glass substrate on a thicker refractive-index matched polymer light guide in order to minimize the amount of glass in the display and thus reduce cost and improve handling. The foil display uses a glass substrate that serves both as a light guide, and as a substrate for the switching electrodes (ITO). Glass has many advantages. It is easily processed, and it is commonly used also in for example LCD's. By contrast, many thin film layers can not easily be processed on plastics. However, the use of the substrate as a light guide brings new limitations as compared to the use of glass substrates in LCD's where an additional substrate is used as a light guide. Foremost, the light guide material must have a very high optical transmission, since the path length of light through the light guide is large. Cheap solutions such as normal window glass can, therefore, not be used. Special glass which is also used in LCD manufacturing is very expensive. The thickness of the glass in LCD's is usually chosen to be as thin as technologically possible (0.5-0.7 mm), in order to reduce display thickness, wei...