Advantages and disadvantages of liquid crystal display

Advantages and disadvantages of liquid crystal display

The traditional CRT display has been developed for decades, and its technical structure principle limits its further development. Several main disadvantages inherent in vacuum cathode ray tube make it more and more difficult for CRT display to adapt to the further improvement of consumer's requirements for display. At this time, flat panel display devices have sprung up, among which liquid crystal display is most likely to replace CRT display in PC display terminal.

The display principle of LCD is quite different from CRT display. Compared with CRT display, LCD display has the following absolute advantages:

1, zero radiation, low energy consumption and small heat dissipation. The display principle of liquid crystal display is to restore the picture by twisting the deflection angle of liquid crystal molecules in liquid crystal pixels, unlike CRT, which has ultra-high voltage components, so that the X-rays caused by high voltage do not exceed the standard. Moreover, the circuit structure is simple, modular, and the chip integration is high 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 small. Although the liquid crystal display may produce slight electromagnetic radiation when working, it can be easily solved by shielding circuit. Due to heat dissipation, CRT monitors should not leak radiation by drilling holes in the shield.

2, slim and light. The appearance of liquid crystal display made the invention of portable computer possible. Similarly, although the LCD of desktop computer is larger in size and weight than that of notebook computer, it is dwarfed by the stupid and heavy CRT monitor. Compared with 15 inch display, the depth of CRT display is generally close to 50 cm, while the depth of Jaws latest LCD NF- 1500MA is less than 5 cm! With the change of consumption concept and living environment, people have higher and higher requirements for the size and weight of household appliances. Liquid crystal display (LCD) has become the most likely display device to break the monopoly of CRT display because of its natural advantages of thinness.

3, accurately restore the image. Liquid crystal display (LCD) adopts the display mode of direct digital addressing, which can directly display video signals one-to-one on LCD pixels on the screen according to the "address" signal in the signal level after AD conversion. CRT monitors rely on the electromagnetic field generated by deflection coils to control the periodic scanning of electron beams on the screen, so as to achieve the purpose of displaying images. Because the trajectory of electron beam is easily influenced by environmental magnetic field or geomagnetism, it is impossible to realize the absolute positioning of electron beam on the screen. Therefore, CRT displays are prone to geometric distortion, linear distortion and other phenomena that cannot be fundamentally eliminated. However, LCD does not have this possibility. Liquid crystal display can perfectly present the picture on the screen without any geometric distortion or linear distortion.

4. The displayed characters are clear. The picture is stable and does not flicker. The unique display principle of liquid crystal display determines that every pixel on its screen emits light evenly, and the red, green and blue pixels are arranged closely. The video signal is directly sent behind the pixel to drive the pixel to emit light, and the phenomenon of poor convergence and focus inherent in traditional CRT displays will not occur. Therefore, the text display effect on LCD is far from that of traditional CRT display. The font of LCD is very sharp, and there will be no font blurring and font flooding when CRT displays text. Moreover, since the LCD always emits light after being electrified, the backlight works at high frequency, and the display screen is stable and does not flicker, which is beneficial to using the computer for a long time. CRT displays emit light by repeatedly hitting the phosphor with electron beams, which will cause the brightness to flicker periodically. Long-term use is easy to cause discomfort to human eyes.

5, the screen is easy to adjust. The direct addressing display mode of LCD makes the screen adjustment of LCD not need much geometric adjustment, linear adjustment and position adjustment of display content. Liquid crystal display, the chip can easily and automatically adjust the screen to the best position after calculation. You just need to press the "automatic" button to complete this step. Save the tedious adjustment of CRT display. You only need to manually adjust the brightness and contrast of the screen to make the machine work in the best condition.

With these natural advantages, liquid crystal display has posed a sufficient threat to CRT display. The only regret is that the price of LCD is still relatively high at present due to the limited manufacturing cost of LCD.

Disadvantages of liquid crystal display

At present, there are many low-priced 14 and 15 inch LCD monitors on the market, and many businesses have also touted LCD to the sky. It is true that liquid crystal displays have many obvious characteristics, but for various reasons, the low-priced liquid crystal displays currently sold are only "low-end" liquid crystal products with many inherent shortcomings. Let's take a detailed analysis of the shortcomings of these LCDs.

1, price

Although it is low-priced, compared with CRT, the price of liquid crystal display can be described as "noble price" in the display family. 15 inch is only 3000 yuan, while the flat panel display of the same size is only about 1000 yuan. According to experts' analysis, the main reason for the high LCD screen is the low yield in the manufacturing process, which makes it impossible to reduce the cost. At present, only some manufacturers in Japan and Taiwan Province Province can produce LCD screens, and the technology has not been fully popularized, and the competitive situation of large-scale production has not yet formed, and the quality is also very different. In the international market, the price difference between different grades can reach tens to hundreds of dollars.

Step 2 connect

The digital interface of LCD is too high to be cold. Theoretically, LCD is a pure digital device, and the connection with the computer host should also adopt a digital interface. The advantages of adopting digital interface are self-evident. Firstly, it can reduce the signal loss and interference 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 liquid crystal displays sold in the market at present use analog interfaces, which have some problems, such as the transmission signal is easily disturbed, the display needs to add analog-to-digital conversion circuits, and it cannot be upgraded to digital interfaces. In addition, in order to avoid pixel flicker, the clock frequency and vector must be completely consistent with the analog signal.

In addition, the digital interface of LCD has not yet formed a unified standard, and graphics cards with digital output are rare in the market. This makes it difficult to give full play to the key advantages of LCD. At present, the result of early consumption is to spend a high price on a monitor.

3. Small viewing angle

The visual deflection angle of early LCD is only 90 degrees, which can only be seen from the front, and there will be great brightness and color distortion from the side. At present, the visual deflection angle of liquid crystal displays on the market is generally around 140 degrees, which is enough for personal use, but if several people watch it at the same time, there will be distortion problems.

4, the corresponding time is too slow

Response time is a special index of LCD. The response time of liquid crystal display refers to the speed at which each pixel of the display reacts to the input signal. If the response time is short, the image tailing phenomenon will not appear when the moving picture is displayed. This is very important when playing games and watching fast-moving images. Fast enough response time can ensure the continuity of the picture. At present, the response time of ordinary LCD in the market has made a great breakthrough, generally around 40 ms, but it still can't meet the requirements of 3D games and high-quality DVD movies.

5. Low brightness and contrast

Do you want a flashlight? This joke is about the brightness and contrast of LCD. Because liquid crystal molecules themselves cannot emit light, liquid crystal 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 explained here that some small-sized LCD monitors were mainly used in notebook computers, and the adjustment of two lights, brightness and contrast were not very good.

6, maintenance problems

Liquid crystal "bad point" problem. Generally, LCD screens are made of glass, which is easily broken. In addition, each pixel is very small, and individual pixels are often broken, commonly known as "bad points". This is beyond repair. Only the entire display screen can be replaced, and the replacement price is often expensive.

The introduction of new products has its advantages over old products. The advantages of LCD are lightness, simplicity and environmental protection. However, due to the defects mentioned above, LCD products can not meet all the needs of consumers. Under the premise of such product technology, we appeal to consumers not to blindly follow the trend, but to recognize their own needs and product characteristics and make the most objective and practical choice.