Liquid crystal display (LCD)
1970, Fergason made the first practical LCD. Before that, LCD had many disadvantages: too much power consumption, short service life and low display contrast. It was not until 197 1 that liquid crystals were accepted by the public and began to spread. LCD uses a liquid crystal screen to display images, and the liquid crystal screen changes the refraction of light with the change of power supply voltage to produce color changes. The LCD screen consists of two layers of glass or plastic panels with liquid crystal sandwiched between them, through which light can pass. After the current is turned on, the liquid crystal can change its direction to control the passage of light, so that the liquid crystal can adjust its color. LCD screens are usually used in portable computers or multimedia projectors. Most flat panel LCD monitors of desktop computers use LCD technology.
The early LCD screen was unstable and not suitable for mass production. It was not until British scientists discovered the stable liquid crystal material "biphenyl" that liquid crystal technology made a qualitative leap. Liquid crystal displays are widely used in computers, game devices and watches.
Plane is beauty.
At present, liquid crystal displays are popular because of their full plane, active array and ultra-thin. LCD has a history of 30 years. Due to the slow research and development in the past, liquid crystal displays are not popular because they cannot provide good image quality. But today, the demand for LCD is increasing, and it is becoming more and more popular. Because of its beautiful appearance, slim appearance, no space occupation and low energy consumption, it is welcomed by people. Now, a large number of well-funded users are using it.
At present, many consumers hold a wait-and-see attitude. They are waiting for the price of LCD to drop, and hope that LCD can provide better performance in brightness, definition and contrast. Only in this way can they transition from the traditional CRT display to the LCD display. Early LCD technology was slow in response, low in efficiency and low in contrast. Moreover, the early matrix technology is passive matrix, which can provide sharp text display, but it will leave a residual image after displaying moving objects. Today, most black and white notebooks, pagers and mobile phones use passive matrices. Because LCD can provide clearer words and clearer images than CRT.
There are two kinds of liquid crystal displays: DSTN (double super twisted nematic) and TFT (thin film transistor), which are called passive and active displays. The LCD is composed of the following layers, which are arranged in the following order: polar filter, thin glass plate, electrode, orientation layer, liquid crystal, orientation layer, electrode, thin glass plate and polar filter.
Early laptops used an 8-inch passive black-and-white display. However, the mainstream of LCD display is developing towards active matrix and large-size display. Nowadays, almost all liquid crystals adopt TFT panels, which can improve the brightness and keep the sharp display effect under large size.
Working principle of liquid crystal display
The cross section of TFT LCD is like many layers of sandwiches stacked together. The outermost layer of each side is a transparent glass substrate, and a thin film transistor is in the middle of the glass substrate. Color filters and liquid crystal layers can display three basic colors: red, blue and green. Usually, there is a light behind the LCD to display the picture.
Generally, as long as the current is constant, the liquid crystal is in an amorphous state. At this time, the liquid crystal allows any light to pass through. After the liquid crystal layer is affected by the voltage change, the liquid crystal only allows a certain amount of light to pass through. The reflection angle of light is controlled according to the liquid crystal.
When the power supply voltage of liquid crystal changes, the liquid crystal will be deformed, so the refraction angle of light will be different, resulting in color change.
A complete TFT display screen consists of many pixels, and each pixel is like a transistor that can be switched on and off. In this way, the resolution of TFT display screen can be controlled. If the resolution of LCD can reach 1024 x 768 pixels (SVGA), it will have so many pixels to display.
What is a liquid crystal display
Liquid crystal display has a brand-new appearance style. Traditional displays using cathode ray tubes are limited by technology and must have their own bloated tubes. Nowadays, flat panel display manufacturers give full play to their imagination and make their products have different design concepts and styles.
A CRT monitor with a thickness of 15 inch and a weight of 30 pounds is at least 7 inches thicker than an LCD with the same display area and weighs 12~ 13 pounds. We can see the advantages of LCD. They also have no problems such as optics and focusing of CRT, and can easily use high resolution in a small display area. For example, a 17-inch LCD can work normally at 1280 x 1024, while a 18-inch LCD cannot work normally above 1280 x 1024. Similarly, the latest LCD is all digital, which is different from CRT, that is to say, the graphics card with digital output can directly output numbers. Theoretically, more accurate color information and pixel position can be obtained. Now there are more and more digital output graphics cards on the market, so it is easy to choose an all-digital solution.
Advantages of liquid crystal display
LCD monitors consume less power.
Unlike CRT, it does not produce electromagnetic radiation.
It doesn't flicker like CRT.
Very small in size and light in weight.
Large visual area
Other differences
Resolution: Under the same display area, CRT can display higher resolution than LCD. LCD can only display one resolution in full screen mode, that is to say, when a standard LCD with 1024 x 768 pixels displays 640 x 480, only 66% of the total display area is used.
Diagonal dimension: The visible area of LCD can be obtained by directly measuring diagonal. The viewing area of CRT also includes a part of the width of its casing.
Signal: CRT uses analog signal and LCD uses digital signal.
Anti-flicker: LCD displays high-quality images without flicker, and users' eyes will not be tired when using them.
How to choose LCD?
To buy an LCD, you'd better look at it yourself first, and then evaluate whether an LCD is worth buying according to the following indicators.
Bad spots: Flat panel LCD may have some bad spots or defective pixels. Those bad spots always show a single color, so we can find them easily. Bad spots are inevitable defects in LCD manufacturing process. The acceptable bad spots on each monitor cannot exceed 3. In some cases, bad spots are very annoying, especially when we watch movies with LCD. If users don't like the bad spots on the LCD, it's best to check them before buying.
Display angle: If you have ever used a notebook, you will know that LCD can provide the best display effect at some angles. Some liquid crystal displays have a wide viewing angle, so you can directly see the contents on the screen from a distance. Notebook users want their monitor to have a smaller display angle, and they don't want the people next to them to see what is on their screen. The general display angle is 120 degrees.
Contrast: LCD itself cannot emit light, and the screen is illuminated by backlight. A gloomy display screen does not mean that there is no backlight; That is, light does not pass through the liquid crystal layer, and no pixels are displayed. Contrast refers to the transmittance level of LCD. The general contrast ratio is 250: 1.
Brightness: the brightness of LCD can be higher than that of CRT. The maximum brightness of LCD is generally 225 c/m2, which is much brighter than TV screen.
Display size-Like traditional CRT, LCD measures display size according to diagonal distance. However, it should be noted that the display size of LCD does not include the shell width like CRT. So a 15. 1 "LCD is a complete 15. 1" screen (which can display 1024 x 768 pixels). 17. 1 inch LCD can display 1280 x 1024 pixels.
Liquid crystal display product recommendation
There are many manufacturers producing liquid crystal displays. The famous ones are: Youpai, Sony, Silicon Map, Samsung, Nec, Eizo Nano and Apple. You may not want to use LCD, but LCD is the most fashionable thing now. Like Laura in Tomb Raider, Sony N50 is everywhere in her castle. Don't you think it's cool to use LCD? Here are some LCD models I recommend. 1
Uniview VP 18 1- is expensive, multifunctional, supports TV, VCD and DVD input and output, and has a built-in microphone. 18 "
Sony l181-very thick and expensive, and uses Tylenol technology,-18 "
Sony m 8 1- thin-18 "
Sony N50- looks very formal and generous, with a thickness of 1.2cm- 15 ".
Sony N50PS- regular and light appearance, thickness 1.2cm- 15 "
Sony N80- thickness 1.2cm, beautiful, expensive and high quality-18 "
SGI1600SW-mainly used for design, with high specifications and high price, which is very attractive-17 "
Samsung 17 1MP- can watch TV. Compared with other products, the price is lower and the design is unique-17 "
Eizo nano-elegant in appearance and expensive-18 "
Apple Cinema Monitor-High Pixel, Wide Screen and Unique Design -22 inches
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