The traditional CRT display has been developed for several decades, and its technical structure has limited its further development. Vacuum CATHODE ray tube inherent several major shortcomings cause CRT display more and more difficult to adapt to the further improvement of consumer demand for displays, at this time, flat panel display devices, the most likely to replace THE CRT display in THE PC display terminal monopoly position is the LCD display.
LCD displays work differently from CRT displays. LCDS inherently have the following absolute advantages over CRT displays:
This paper mainly introduces: graphical LCD advantages and disadvantages
1. Zero radiation, low energy consumption, low heat dissipation. The principle of an LCD display is to restore the screen by twisting the deflection Angle of the liquid crystal molecules in the liquid crystal pixels to the background light. There is no such thing as a CRT with ultra-high pressure components inside, so as not to cause excessive X-ray emission caused by high pressure. Moreover, the machine structure circuit is simple, modularization and high integration of the chip is enough to minimize the electromagnetic radiation generated when the circuit works. This design directly reduces the power consumption of the circuit, and the calorific value is also very low.LCD displays (LCDs), while working, may produce slight electromagnetic radiation, but are easily resolved by shielding circuits.CRT displays are not allowed to leak radiation by drilling holes into the shield for heat dissipation.
2. Thin and light. It was the advent of LCD displays that made the invention of portable computers possible. Similarly, desktop LCDs, while larger in size and weight than laptops pale in comparison to the clunky CRT displays. Compared to a 15-inch display, CRT displays are typically nearly 50 centimeters deep, while the latest GREAT White shark LCD, NF-1500MA, is less than 5 centimeters deep! With the change of consumption viewpoint and living environment, people have higher and higher requirements on the volume and weight of household electrical appliances.LCD display (LCD) is the most likely display device to break the CRT display monopoly because of its thin and light nature.
3. Accurate image restoration. The LCD adopts the direct digital addressing display mode, which can directly display the video signal output from the graphics card on the LCD pixel one to one according to the "address" signal in the signal level after the AD conversion.CRT displays display images by deflecting coils that generate electromagnetic fields to control the periodic scanning of the electron beam on the screen. The absolute positioning of the electron beam on the screen cannot be achieved because the trajectory of the electron beam is easily affected by the environmental magnetic field or geomagnetic field. Therefore, CRT displays are prone to geometric distortion, linear distortion, and other phenomena that cannot be fundamentally eliminated.LCD displays do not. The LCD can present the picture perfectly on the screen without any geometric distortion or linear distortion.
4. display character sharp. The picture is stable and does not flicker. The unique display principle of LCD determines that all pixels on the screen emit light evenly, and the pixels of red, green, and blue primary colors are closely arranged. The video signal is sent directly to the back of the pixels to drive the pixel to emit light, so the convergence and poor focus inherent in traditional CRT display will not occur. As a result, the LCD text display effect compared with the traditional CRT display has a world of difference.LCD font is very sharp, no CRT display text when the font blur, font color phenomenon. Moreover, since the LCD display is always glowing after being powered on, the backlight lamp works under high frequency, and the display picture is stable but does not flicker, which is conducive to the long-term use of the computer.CRT displays emit light by repeatedly striking the phosphor with an electron beam, which causes the brightness to flicker periodically. It is easy to cause eye discomfort after using it for a long time.
5. Easy screen adjustment. The direct addressing display mode of an LCD display makes the screen adjustment of LCD display need not too much geometric adjustment and linear adjustment as well as the position adjustment of display content. The LCD screen can be easily adjusted to the optimal position automatically after chip calculation, this step you just need to press the "Auto" button to complete. Eliminates the cumbersome tuning of CRT displays. You just need to manually adjust the brightness and contrast of the screen to make the machine work at its best.
These natural advantages of LCD displays (LCDs) pose enough of a threat to CRT displays. The only regret is that LCDs are still relatively expensive due to the cost of making them.
Disadvantages of LCD
Now on the market has a lot of low-priced 14 and 15 inch LCD sales, many businesses will also boost to the sky, LCD, admittedly, LCD has a lot of very clear a bit, just because of various reasons, the current sale low price of liquid crystal are belong to the inside of the LCD products "low-end", itself has many inherent shortcomings, let's analyze in detail exactly what are the disadvantages of the LCD display.
1. price
Although said to be low price, but he CRT compares, the price of the LCD display is in monitor family it may be said "noble price", it is 15 inches only 3000 yuan, and the flat display of the same size also does not cross 1000 yuan or so. Experts say the high quality of LCD screens is mainly due to the low yield rate in the manufacturing process, resulting in the cost cannot be reduced. At present, only Some manufacturers in Japan and Taiwan are able to produce LCD screens, the technology has not completely spread, there has not been a competitive situation of mass production, and the quality is also very different. In the international market, the price difference between different grades can be as much as tens to hundreds of dollars.
2. interfaces
Digital interfaces for LCD displays (LCDs) are lonely at the top. Theoretically speaking, LCD display is pure digital equipment, and the connection of the computer host should also be to use digital interface, the advantage of using a digital interface is self-evident. Firstly, the signal loss and interference can be reduced in the process of analog-to-digital conversion. Reduce the corresponding conversion circuits and components; Secondly, there is no need to adjust the clock frequency and vector.
However, most of the low-priced LCDs on the market use analog interfaces, which have problems such as vulnerable signal transmission interference, the need to add analog-to-digital conversion circuits inside the display, and the inability to upgrade to digital interfaces. Moreover, in order to avoid the occurrence of pixel flicker, the clock frequency, vector, and analog signal must be completely consistent.
In addition, LCD digital interfaces have not yet been standardized, and display CARDS with digital output are rare on the market. Come so, the key advantage of the LCD display is brought into full play hard, however. For now, the result of early consumption is a costly display.
3. Small viewing Angle
Early LCDs had a visual deflection Angle of only 90 degrees and could only be viewed from the front, with greater brightness and color distortion when viewed from the side.LCD displays now on the market typically have a visual deflection Angle of about 140 degrees, which is enough for personal use, but if several people are watching at the same time, the problem of distortion becomes apparent.
4. The corresponding time is too slow
Response time is a special indicator of LCD. The response time of the LCD display refers to the response speed of each pixel of the display to the input signal. If the response time is short, there will be no image trailing when displaying the moving picture. This is important when playing games and watching a fast-moving video. A fast enough response time ensures a consistent picture. At present, the response time of ordinary LCD HMI displays on the market has made a great breakthrough compared with the previous ones, which is generally about 40ms. But it still fails to meet the demand for 3D games and high-quality DVD movies.
5. Low brightness and contrast
Do you want a flashlight? The joke is about the brightness and contrast of LCD monitors. Since liquid crystal molecules cannot emit light by themselves, LCD displays need to rely on external light sources to assist in emitting light. Generally speaking, 140 lumens per square meter is enough. There is still a gap between the parameter standards of some manufacturers and the actual standards. It should be noted that some small LCD used to be mainly used in laptop computers, with two lights adjustment, so their brightness and contrast are not very good.
6. Maintenance problems
Liquid crystal "bad point" problem. The material of the LCD display screen is generally made of glass, which is easy to be broken. In addition, every pixel is very small, which often causes the phenomenon of individual pixels being broken, commonly known as "bad point". This is not repairable, and only the replacement of the whole display screen is often very expensive.
The launch of a new product has its own advantages over old products. The advantage of an LCD display is that it is light, simple, and environmentally friendly eye protection. However, due to the current LCD products at the same time, there are defects, not enough to meet all the needs of consumers. Under the premise of such product technology, do not blindly follow the fashion trend, but to recognize their own needs and product characteristics, to make the most objective and practical choice.
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