In recent years, the LCD TV working principle, the advantages and the evaluation standard have been in recent years, since the key technology of the liquid crystal screen has continuously achieved the breakthrough and the price decline, the liquid crystal television has completely replaced the crt television in the home, office, shopping mall, hospital, The dominant position of government organs in the field of application has become the standard product for all major enterprises. The rapid spread of liquid crystal television products means that a new learning task is before us for the maintenance of our technical services. Now let's get together to learn the working principles and advantages of the LCD TV. from the above figure we can know that the lcd tv has the following several parts on the internal circuit structure:1, a drive plate (also called a main board): mainly for receiving, processing analog (vga) or digital (dvi) video signals from the outside, And controls the normal operation of the liquid crystal panel by the screen line sending signal. The drive plate contains the mcu unit, which is the detection control center and the brain of the liquid crystal display. 2. Power panel: used for converting the AC voltage of 90-240v to the DC power supply TV set of 36v, 18v, 24v 12v, 5v, 3v, etc. 3. The back light plate (also called high-voltage plate): The high-voltage alternating current for converting the DC voltage of 36v, 24v, 18v, and 12v output by the main board or the power board into high-frequency power of 1500v-1800v, which is required by panel, is used to turn on the backlight of panel.
The power panel and the backlight are sometimes used together as the so-called power source backlight two-in-one board. 4. Liquid crystal screen: a liquid crystal display module, which is a core component of a liquid crystal television, which comprises a liquid crystal panel and a driving circuit. The LCD is the most critical part of the LCD, and it plays a decisive role in the performance and price of the LCD. Liquid crystal display (LCD) is the working principle liquid crystal television (lcd), which refers to a television with a liquid crystal screen as a display. The LCD TV screen is composed of more than two million red, green, and blue three-color liquid crystal light valves. The liquid crystal light valve is activated at extremely low voltage. At this time, the light beam emitted from the back light behind the liquid crystal screen is passed from the liquid crystal screen to produce a 1024-768-768 lattice (0.297 mm from the point), with extremely high resolution. At the same time, the advanced electronic control technology causes the liquid crystal light valve to produce 1677 million kinds of color change (red 256-green 256-blue 256), restore the real brightness, color degree, and reproduce the natural and pure picture. The liquid crystal display has fundamentally changed the "line"-based analog scanning mode of the traditional color TV set, and the digital display technology based on the "point" is realized. The liquid crystal television has the advantages that the liquid crystal television has the following advantages compared with the traditional picture tube (crt) television: the screen is stable. The field and the line scanning mode are removed, so that the picture flicker and the instability caused by the scanning are avoided; and the image is vivid. The digital lattice display mode is adopted, and the geometric distortion rate of the picture is reduced to zero. The high-brightness, high-contrast and anti-reflective liquid crystal screen is adopted, so that the brightness and the contrast of the television picture are greatly increased. The reflection and scattering of light can be reduced, and a brighter, clear and delicate picture can be seen; and the radiation can be eliminated.
The fluorescent lamp is used for imaging through the liquid crystal screen, and the radiation and the static electricity generated by the crt electron beam high-voltage accelerated bombardment fluorescent powder are completely eliminated; and the space is saved. The large crt and other components are thrown out, the thickness of the whole machine body is not more than 6cm, the thickness of the whole machine body can be pasted on the wall, and the storage space can be saved, and the energy consumption can be saved. The maximum power consumption of the LCD TV is 65w, which is 70% less than that of the traditional TV, and is very popular with the consumer. The following maintenance costs, parts, and accessories are quite complete with respect to our service industry (6). For customers, because the feeling screen is large, the function is much, the machine is valuable, so the maintenance cost we charge is often relatively high. (7) The working principle is simple and the internal structure is composed of five six-piece circuit board. It is easy to learn and understand. As long as everyone is interested in the LCD TV for a month to ensure that the students can learn very well. (8) The working principle of the switching power supply of the LCD TV is learned, and the use is very large, such as office equipment, computer and household appliances are all used in the switching power supply. The saying goes through all the time. The liquid crystal panel (LCD) principle liquid crystal is a substance between solid and liquid, and is an organic compound having a regular molecular arrangement. If it is heated to present a transparent liquid state, it is cooled to give a turbid solid state of the crystalline particles, with the properties of the liquid and the crystal, which is referred to as a "liquid crystal". The principle of the liquid crystal display is that the liquid crystal arranged between the two electrodes is electrified, and the arrangement order of the liquid crystal molecules is changed when the electrode is electrified, so that the light path of the transmitted light is changed, and the control of the image is realized. The liquid crystal panel can be divided into passive matrix (passive matrix) lcd and active matrix (with source matrix) lcd according to different control modes. The passive matrix lcd can be divided into three types of tn-lcd (twisted nematic-lcd), twisted nematic (lcd), stn-lcd (super tn-lcd), super-twisted nematic (lcd), and dstn-lcd (double layer stn-lcd). The principle of tn, stn, dstn liquid crystal panel is basically the same, except that the twist angle of each liquid crystal sub-sub is slightly different, where dstn (commonly known as "pseudo-color") is widely used in the early-stage notebook computer display and the palm top game machine. the passive matrix lcd has the advantages of small viewing angle, slow response, high picture quality and the like due to the fact that the passive matrix lcd can be developed by using an external light source, so that the display device is not beneficial to the development of the desktop type display, but the passive matrix lcd is low in cost, A few displays in the market have adopted a passive matrix lcd. for passive matrix lcd, since it can be made thinner and lighter and more power-saving,