For many years now, TFT LC-Displays have been the dominating technology in visualization. With more and more screens being used outdoors and in portable applications, sunlight readability has become a critical factor in the display market. One way many LCD manufacturers address this issue is to increase the display’s backlight luminance. Although this works well for many applications, it also increases power consumption and the bulkiness of the display. This is not an ideal solution for some portable or small-size applications, so NVD additionally offers “transflective” displays, which have improved readability in any lighting condition without increasing power consumption or bulkiness.
Simple, low resolution liquid crystal displays routinely are offered in reflective, transmissive, and “transflective” (partially transmissive and partially reflective) mode. This is achieved simply by choice of the reflector behind the display , which is usually attached to the rear polarizer. This method is not feasible for TFT displays due to the inherently much lower transmission of these devices. Transflective TFT displays have a unique cell architecture compared to standard TFT display modules. This is necessary to accommodate for the fact that light passes only once through the liquid crystal layer in transmissive mode before reaching an analyser, while in reflective mode it passes the liquid crystal layer twice. In the transflective cell architecture, every single pixel is divided into a transmissive and a reflective section, where the latter is based on a polymer film with micro metal mirrors within the glass cell. The size and partition of these two sections are flexible and depend on the desired focus of the final display. Typically the liquid crystal layer thickness in the reflective part is only half of the call gap in the transmissive part. The front polarizer acts as both, polarizer and analyser for the reflective portion of each pixel. This requires selection of a liquid crystal mode that works with parallel polarizers, unlike transmissive displays where usually polarizer and analyser are crossed.
Image 1 — Transflective Display Cell Architecture
Written By Frank Jammers (FAE for Europe) and Matthias Pfeiffer (CTO) at New Vision Display
Article Source: http://goo.gl/HBdWM7
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