Analysis:
Advantages and disadvantages of liquid crystal display
Liquid crystal display is a new display device which is completely different from CRT in display principle. Compared with CRT display, LCD display has the following absolute advantages:
1. Small size and light weight. The structure of liquid crystal display is simple, even for large-screen liquid crystal display, the thickness of its finished product is less than 20 cm. However, the CRT display is low, and the polarization angle of the electron beam cannot be blindly increased because of the need to accurately control convergence and focusing. Therefore, the larger the viewing area, the greater the depth of CRT display. For example, the depth of a 19 inch CRT monitor exceeds 50 cm. This is a great waste of office space.
Low power consumption, small heat dissipation, and the power consumption of LCD can be controlled below tens of uW/cm. Generally, the working power of 15 inch LCD is about 30W, and that of 17 inch CRT is above 100W. In addition, after long-term operation, the calorific value of LCD is much lower than that of CRT.
13. accurately restore the picture with sharp words. Whether visually or physically, LCD is essentially a full-screen display. It is completely different from the working principle of CRT, and fundamentally avoids the geometric distortion and nonlinear distortion of image restoration. However, due to the glass on the screen, the CRT display cannot be made too thin. At present, flat CRT displays are not completely flat. Even the flat-panel Terilon and flat-panel Diamondtron displays, which perform best in visual compensation, can only ensure "visual flatness" at a fixed viewing angle and viewing distance. Moreover, it is almost impossible to accurately control the electron beam to hit the corresponding phosphor spot after a long trajectory, and geomagnetic and surrounding electromagnetic fields are also very easy to interfere with the trajectory of the electron beam. Therefore, when the electron beam hits the center screen and edge of CRT display, the path and angle of electron beam movement are different. Even through complex dynamic focusing, the electron beam's landing point around the screen cannot be the same as the point in the center of the screen. Therefore, the focus of CRT display in the center of the screen is always better than that at the edge of the screen. Moreover, after the RGB three electron beams are deflected at a large angle, perfect convergence cannot be guaranteed in any area of the screen. Poor convergence may easily lead to the flooding of displayed text. LCD is directly addressed according to the video signal, so there is no possibility of poor focusing and convergence. Therefore, the displayed text is very sharp, and the picture will not appear color cast.
4. The picture does not flicker. Liquid crystal is a light-receiving display device. The work of the backlight is constant, and only when the screen content changes, the display content will change the distortion of the LCD box. Only the light of the backlight panel can affect the flicker of the picture, and the backlight panel works at a frequency of about 75K. So the LCD screen is very stable and there is no flicker. CRT is an active light-emitting display device, and phosphor will only emit light under the bombardment of electron beam. Even if the phosphor is bombarded at a frequency of 85HZ, staring at the screen for a long time will still cause eye fatigue due to the flicker of the phosphor.
5. Low radiation. Only the driving circuit of LCD may have slight electromagnetic leakage. However, the structure of CRT display is complex, and the electromagnetic leakage is different because of the different working frequencies of each component. The radiation produced by the high voltage of kinescope is harmful to human body even if it meets the most stringent TCO99 standard, but it is still harmful to human body after being exposed to radiation for a long time.
Screen adjustment is simple and convenient. The principle of LCD determines that it does not need as complicated adjustment as CRT. Now the LCD can be adjusted to the best working state according to different working conditions only by pressing the automatic adjustment once, leaving you only to adjust the brightness and contrast according to your personal hobbies. On the other hand, every time a CRT changes its resolution or refresh rate, or even changes its display direction, it must undergo complicated adjustments.
Compared with CRT, LCD has incomparable advantages, but it also has some obvious disadvantages:
1. High production cost and low yield. At present, the production technology of LCD is not fully mature, and the yield is still low. It takes a long time for the expensive LCD panel production line to slowly improve the yield, and the discarded LCD panels cannot be recycled, resulting in high production cost at present. Although many manufacturers in Taiwan Province Province have actively invested in the LCD production industry, the competition has suddenly intensified. In recent years, the price of LCD panels has dropped sharply, but compared with traditional CRT monitors, its price is still slightly higher.
The existence of defects. In view of the current limitations of LCD production cost and technology, industry standards allow LCD to have obvious defects. In fact, at present, CRT manufacturers allow defects in CRT factories. However, due to the maturity of CRT production technology, the possibility of bad spots is very small, even if there are bad spots, they exist in the form of dark spots, which is difficult to find in CRT, an active light-emitting display device. Defects in liquid crystal displays may also be in the form of dark spots.
3. The viewing angle is too small. The light on the backlight board can not only penetrate the liquid crystal pixels vertically into the human eye, but also penetrate the nearby liquid crystal pixels at other angles. When viewing an LCD screen with a certain line-of-sight angle, the contrast and color distortion of the screen will appear, resulting in serious inversion of Yin and Yang. Although the nominal viewing angle of many liquid crystal displays on the market is as high as 65,438+060 degrees horizontally and 65,438+020 degrees vertically, these parameters often
Response time is too long. The response time of liquid crystal includes rise time (Tr) and fall time (Tf). Because the response time of LCD depends on the movement time of liquid crystal molecules, how to reduce the response time of LCD is still a problem to be solved. At present, the overall response time of mainstream liquid crystal displays in the market is generally 40-60ms, which leads to obvious tailing phenomenon when LCD plays back video images or displays game dynamic images. Many manufacturers in the market often use the rise time of LCD as the overall response time to deceive consumers.
5. The maximum number of display colors is insufficient. At present, the liquid crystal display on the market can display at most 8-bit colors for each primary color of liquid crystal pixels through FRC technology, that is, the eighth power of 2 =256 colors, so the maximum number of colors that each group of pixels can display is 256 * 256 * 256 = * * * * * * * * *. It can be seen that the LCD can restore color.
If LCD can be greatly improved in these aspects, I believe it is no longer a slogan to eliminate CRT monitors.
Performance comparison table of displays with different structures
Liquid crystal display, cylindrical display, flat right-angle display, shadow mask flat panel display, shadow mask flat panel display
The writing is excellent, good, good.
The color is good, medium and high, medium and high.
The whole machine is excellent, poor and good.
Good safety, good neutrality and excellent quality.
Coating-excellent quality.
Nonlinear distortion is excellent, medium and medium.
Geometric distortion is excellent, medium and medium.
Corner focusing and convergence-very good
Power consumption excellent difference difference difference difference
Excellent radiation, medium good, good is good.