comparison of liquid crystal display (lcd) and conventional display (crt)

- Oct 10, 2019-

Although the principle of product purchase and display is different, the common purpose of the liquid crystal display (lcd) and the conventional display (crt) is to achieve an excellent display effect, and now we compare the crt and tft liquid crystal display. the structure and the product volume: the conventional crt-type display must emit an electron beam to the screen through an electron gun, so that the tube of the picture tube cannot be too short, the volume must be increased when the screen is enlarged, Even if the screen is enlarged, it only needs to increase the horizontal area, but the volume does not increase significantly, and is much lighter than the crt display, while the tft is only used for the plate and the drive ic because of the power consumption, and therefore the power consumption is small. Radiation and electromagnetic interference: a conventional display generates a radiation source due to the use of an electron gun to emit an electron beam to the screen. Although there are now some advanced technologies to minimize radiation, it is still not completely eradicated. The tft liquid crystal display does not have to worry about that.


 As for the interference of the electromagnetic wave, the tft liquid crystal display has only a small amount of electromagnetic wave from the driving circuit, so that the electromagnetic wave can not be leaked as long as the shell is tightly sealed, and the crt display has to blow out the heat dissipation hole on the machine body in order to heat the heat, so that the electromagnetic interference is bound to be generated. The flatness and resolution of the screen: the tft liquid crystal starts with a pure-planar glass sheet, so the flatness is much better than most crt displays, of course there is a pure-plane crt color display. In resolution, tft is not as much as a crt display, although it can theoretically provide a higher resolution, but that is not the case. 


The display effect: the conventional crt display is much better than the light-transmitting type of the liquid crystal by striking the fluorescent powder through the electron gun, and the crt is better than the tft in the visible angle, and the crt and the tft are very poor at the display reflecting speed. The physical characteristic of the liquid crystal in the liquid crystal display principle 


(I) is that when the liquid crystal is electrified, the liquid crystal is arranged in an orderly way, so that the light is easy to pass; and when the liquid crystal is not electrified, the liquid crystal is arranged in disorder, and the light is prevented from passing through. The liquid crystal, such as a gate, is made to block or allow light to penetrate. Technically, the liquid crystal panel contains two rather delicate, sodium-free glass material, called substrata, with a layer of liquid crystal in the middle. When the light beam passes through the liquid crystal, the liquid crystal itself is arranged or twisted in an irregular shape, thereby blocking or passing the light beam smoothly. Most of the liquid crystals belong to the organic complex and consist of long rod-shaped molecules. In a natural state, the long axes of these rod-like molecules are substantially parallel. When the liquid crystal is poured into a well-processed slotted plane, the liquid crystal molecules are arranged along the grooves, so if those grooves are very parallel, the molecules are also completely parallel. 


(2) The principle of single-color liquid crystal display (LCD) is to fill the liquid crystal between two planes with a slot. The grooves on the two planes are perpendicular to each other (at an intersection of 90 degrees). That is, if the molecules on one plane are arranged in the south-west direction, the molecules on the other plane are arranged in an east-west direction, and the molecules located between the two planes are forced into a 90-degree twist state. Since the light travels in the direction of the arrangement of the molecules, the light is also twisted by 90 degrees when passing through the liquid crystal. But when a voltage is applied to the liquid crystal, the molecules are re-vertically arranged so that the light can be directed out without any twisting. Lcd is a dependent polarization filter (sheet) and light itself. The natural light is scattered randomly in all directions. The polarized filter is actually a series of more and more thin parallel lines. These lines form a net that blocks all light that is not parallel to these lines. The line of the polarization filter is exactly perpendicular to the first, so that the polarized light can be completely blocked. Only the lines of the two filters are completely parallel, or the light itself has been twisted to match the second polarization filter to allow the light to penetrate.