Liquid crystal displays, LCDs pixels

Active matrix displays have a thin-film transistor (TFT) switching circuit embedded in the area of each individual pixel. Although the TFT backplanes needed for polymer emissive displays are similar to those developed for liquid crystal displays (LCDs), the TFT circuits must be capable of switching much higher currents than are required for LCDs. For active matrix displays, the luminescent semiconducting polymer and cathode, etc. are deposited directly onto the premanufactured TFT backplane (the anode for the LED pixel is built onto the TFT circuit). In an active matrix display, the pixels are held at constant brightness by the TFT circuit and the image is refreshed at video rates (e. g. 60 Hz). 

Thin Film Transistor (TFT) Transistors in a liquid crystal display (LCD) that help control the voltage, and therefore, the coloring, at individual pixels. 

The first commercial head-mounted devices were called Eye Phones. They were introduced byjaron Lanier in 1989, sold for the price of 11,000 per set, and weighed 2.4 kilograms. The liquid crystal display (LCD) had a very low resolution-only 360 X 240 pixels. 

The technical specifications of these monitors are impressive they luminesce in the entire visible spectrum, they are bright and efficient. They are thinner and lighter than LCD monitors (liquid crystal displays) and are therefore especially suited for portable equipment. They are intrinsically emissive, and thus require no background illumination, and they have a display angle of nearly 180°. Furthermore, they are fast and thus suitable for rapid video sequences. The image points (pixels) can be switched to a completely dark state, so that higher contrast can be obtained. 

Ferroelectric liquid crystals also show high resolution due to the very thin gaps allowed by their mode of action. In the transmission mode, they are typically less than 2 xm thick, compared to 4-8 xm in nematic LCDs. In reflective ferroelectric liquid crystal displays, this thickness is reduced by half, resulting in a thickness of less than 1 jxm. Thus, pixels as small as 5 xm have been demonstrated. 

Alternative intrinsic threshold LCDs will enable multiplexing up to 100 lines and SxlO pixels. Extrinsic threshold technology will be required to multiplex high information content displays (10 to 10 lines, 10 to 10 pixels) with greater than SxlO pixels. We therefore conclude that high information content flat panel LCDs will not be an evolutionary product of present day FSM TN-LCDs but will require development of a revolutionary generation of liquid crystal displays based on extrinsic threshold control. 

The demands that an AMOLED display places on TFT performance are more stringent than those placed by liquid-crystal or electrophoretic displays. Table 6.4.3 compares the TFT requirements of high-resolution displays of these types. The different TFT requirements arise from the fact that LCD and electrophoretic display pixels have a single TFT that is used as a switch, while an AMOLED pixel has one or more TFTs used as a switch, plus one or more used to drive current. A transistor used as a switch typically has stringent requirements for off-current because it must not leak significant charge when it is off, but the requirements for mobility, uniformity, and stability are modest. A transistor that is used to drive current has stringent requirements for mobility, uniformity, and stability, but off-current requirements are lenient. Because the AMOLED pixel has both types of... 

LCD displays are formed by thin-film techniques in which the liquid crystal layer is surrounded by electrodes which control the alignment of the LC s. If the LCD is a color display, color-filters are used to form a red, green or blue pixel, with athin-film-transistor at each pixel to control the transmission of light at that point. This construction is shown in the following ... 

By far the most important application area of liquid crystals per se is of course in display devices. Who can fail to be amazed at the technological triumph of an active matrix LCD flat projection panel capable of displaying 1024 x 768 pixels X 256 colors Perhaps the insights derived from PLCs will have some impact on displays, or even modulators, nonlinear optical devices or data storage devices. 

Accordingly, D-STN-LCDs fabricated according to these conditions (with micro colour filters on each pixel) were used to make multi-colour LCD displays. It should be noted that a film-compensated STN-LCD using optical retarder films instead of the STN-LCD liquid-crystal compensator in the D-STN-LCD can also be used. 

---