"Computer Graphics" 2.1.5 Flat panel display

A flat panel display (Flat-panel display) represents a class of video devices that can swordsman mention, reduce weight, and conserve power compared to the CRT. A flat-panel display with a meaningfully 1 surname is thinner than the CRT, and can be hung on a wall or on the wrist. Some flat-panel displays can even be written, so they can be used in other places such as pocket-sized notebooks. We can divide the flat xian four into two categories: the launch display (emissive display) and the non-transmitting display (nonemissive display). A transmitting display is a device that converts electrical energy into light energy. Plasma displays, thin-film photoelectric displays, and light-emitting diodes are examples of emission displays. The flat-plate CRT has also been invented, in which the electron beam accelerates in parallel to the screen, then deflected 90 ° to bombard the screen. However, it has not been confirmed that the flat-panel CRT can be practically applied as other transmitting devices. A non-transmitting display uses optical effects to convert sunlight or light from some other Guangyuan into a graphical mode. The most important example of a non-emitting flat panel display in a liquid crystal device room. A plasma display (plasma panel), also known as a gas discharge display (Gas-discharge display), is formed by filling the area between two glass panes with a gas mixture normally containing neon gas. A glass plate is placed on a column of vertical conductive bands, and a group of horizontal conductive bands is constructed on the other glass plate (Fig. 2.11). The ignition voltage is applied at the level of acceptance and the vertical conductive band, causing the gas at the intersection of the two conductive bands to enter the electron and the glow-point plasma of the example. The definition of the graph is stored in the refresh cache, where the ignition voltage refreshes the pixel position at a rate of 60 times per second (intersection of the conductive band). Using the quibble current method to provide the ignition voltage quickly, a brighter display can be obtained. The separation between pixels is provided by a power plant with a conductive belt. The plasma display board has one drawback, namely that it is a strict monochrome device, but has now developed a plasma display that can display color and grayscale levels. [Figure 2.11] The thin-film photoelectric display (Thin-film electroluminescent display) has a similar structure to the plasma display plate. The difference is that the area between the panes of glass is filled with fluorescent material, such as zinc sulfide and manganese gels, instead of gas (fig. 2.13). When a high enough voltage is added to a pair of crossed electrodes, the fluorescence layer is called a conductive body in the intersection area of the two electrodes. Energy is absorbed by a fierce atom, and then the energy released is called a luminous two point, which resembles the glow effect of a good IU light discharge of a plasma display plate. The photoelectric display needs more power than the plasma display board, and it is difficult to achieve good color and gray level display. [Figure 2.13] The third type of transmitting device is a light emitting diode (light-emmitting diode,led). The diode is arranged in a matrix to form the pixel position of the monitor, the definition of the graph is stored in the refresh cache. Like the CRT scan line refresh, the information is read from the brush-Rage Han Cun, converted to voltage level, then applied to the diode, a luminous pattern on the display, and a liquid crystal display (Liquid-crystal DISPLAY,LCD) are typically used in small systems such as laptops and calculators. The principle of these non-transmitting devices to generate graphics is to pass polarized light from either the known or the internal light source through a liquid material that can block or pass through the lights. The term liquid crystal (Liguid srystal) refers to these compounds have crystalline structure of the molecule, and can flow like a liquid. Flat panel displays typically use the current liquid crystalline compounds, which tend to maintain the long axis arrangement of rods. As a result, the flat panel monitor is available in the current LCD composition, shown in 2.15. There are two glass panes, each with a light polarizer, with the other to form a suitable angle, the interior is filled with liquid crystal material. The horizontal transparent conductor line is discharged on a board and a vertical transparent conductor row is placed on the other board. Defines a pixel position at the intersection of the row and column conductors. Normally, the molecules are arranged in the "open state" as shown in Figure 2.15. The biased light passing through the material is distorted so that it passes through the opposite polarizer, thus reflecting the light to the observer. If we want to turn off the pixels, we can place the voltage on two intersecting conductors, aligning the molecules so that the biased light is no longer distorted. This type of flat panel display device is visible as a passive matrix (Passive-matrix) LCD. The definition of the graph is stored in the refresh cache, which refreshes the screen at a rate of 60 frames per second, the same as the transmitting device. When using solid state electronic devices, the backlight is often used, and the system is not completely dependent on the external Guangyuan. You can use different materials or fuels to display colors, and place a triad of color pixels at each screen position. Another way to make the LCD is to put a transistor in each pixel position and use thin-film transistor technology. Transistors are used to control the voltage at the pixel position and to prevent chronic leakage of the yajing unit. These devices become active matrix (Active-matrix) displays. [Figure 2.15]

Computer graphics 2.1.5 Flat Panel display