The main features of liquid crystal displays Compared with traditional CRT displays, liquid crystal displays have the following advantages:
1. Space-Saving Traditional Displays Due to the use of CRTs, electron beams must be emitted from the electron guns to the screen, so the tube neck cannot be made too short. When the screen size increases, the volume and weight of the entire display will be drastically increased. The TFT liquid crystal display shows through The electrode on the screen controls the state of the liquid crystal molecules to achieve the purpose of display. Even if the screen is enlarged, its volume will not increase proportionately. In general, the thickness of the LCD display, regardless of the size of the screen, is controlled within 20 cm, and The CRT display is also much lighter in weight than the same display area.
2. Energy-saving CRT displays require heating the electrode elements so that the electron gun emits electron beams at a very high speed, so we often feel that the CRT generates a lot of heat. This is also the main reason for the energy consumption of the CRT. The TFT liquid crystal display consumes only the electrodes and the driver due to the power. On the IC, therefore, the power consumption is much smaller than that of a conventional display. A 15-inch LCD monitor consumes about one quarter of the power of a 17-inch CRT monitor. Taking into account the fact that the LCD monitor can reduce air-conditioning and cooling costs, the power-saving effect is quite obvious, and the total cost of ownership of the product is reduced. Very favorable.
3. This is the greatest advantage of LCD monitors for health benefits. Traditional monitors use electron guns to emit electron beams and hit the screen with radiation. Although CRT monitors have many ways to reduce radiation, they still cannot be cured. At this point, TFT liquid crystal display has inherent advantages, it is basically called "zero radiation" products, only a small amount of electromagnetic waves from the drive circuit, because the liquid crystal display does not need to open the cooling holes, as long as the housing is sealed and can be ruled out Electromagnetic leaks. TFTLCD has no radiation, no flicker, plus soft colors, can effectively reduce the eyes of the user's fatigue, LCD can really be called a healthy display, so in some places sensitive to radiation problems, such as the stock exchange, hospitals and other units, The LCD display is widely used. With people's increasing attention to their own health and the gradual decline in the price of LCD displays, it is believed that more and more people will choose LCD displays.
4. The unique display style First of all, the LCD is a completely flat display. The liquid crystal display technology not only eliminates bulky kinescopes, but also uses a flat glass plate. It does not have any directional protrusions. It is flat and lightweight, and the LCD display is clear and soft. There is a more realistic and saturated color effect and the image quality is more accurate. Many friends like the unique display style of LCD monitors. Compared with CRT monitors, the lack of LCD monitors mainly in the following two points: 1. The display effect is not enough. Because the display screen of the conventional display uses a phosphor, the electron beam hits the phosphor and displays an image, and thus is brighter than the translucent display of the liquid crystal, and the color is more vivid, especially at the viewing angle. TFT liquid crystal displays are much better (almost no visual angle problem). In displaying the reaction speed, the traditional display is also more advantageous, with almost no delay.
2. The price is too expensive The current LCD monitor's biggest disadvantage is its price. The same size LCD is much more expensive (about 3 times) than the CRT, and it is not easily affordable by the general public.
Second, the purchase of liquid crystal display points Because LCD and CRT are completely different in the working principle, LCD display on the purchase, both similar to the ordinary CRT monitor notes, there are some special points for purchase. When purchasing an LCD monitor, it is important to first examine the special technical features that are different from ordinary CRT monitors.
1. The size of the viewing angle Due to the display principle, the LCD monitor must be viewed from the front to obtain the best visual effect. If viewed from other angles, the screen will have different degrees of dimming, color changes and other issues. The visual range refers to the clear angle range from the middle of the screen to the top, bottom, left, and right directions. The larger the value is, the more naturally the range is, but the range of the four directions is not necessarily symmetrical. In general, the viewing angle of 140 to 160 degrees should be the basic indicator of the LCD monitor. In addition, the horizontal and vertical viewing angles should preferably be the same.
2. Brightness and Contrast The higher the brightness value, the more natural the picture is. The unit of brightness is della (cd/m2). The general LCD luminance value is about 150cd/m2, and some can reach 250cd/m2 or more. At present, the brightness of TFT liquid crystal displays that can be seen in China is basically around 200cd/m2. LCD brightness has a great influence on the display. Also note that some LCD displays have uneven brightness and are very bright at the center of the screen, but at the edges, the brightness is reduced a lot and you should be careful when purchasing. The higher the contrast, the more vivid and saturated the colors, and the three-dimensional appearance. The contrast is low, the colors appear poor, and the images become non-stereoscopic. The current LCD contrast ratios vary widely from 100:1 to 300:1 or even higher. However, the contrast is not as high as possible. To achieve a good image quality, it must be matched with the brightness.
3. The reaction speed response time reflects the speed of each pixel of the liquid crystal display responding to the input signal. The smaller the value, the better. The smaller the response time is, the faster the motion picture is displayed will not make the user feel the tail drag. The unit of measurement response or recovery time is milliseconds, which is the time required for a single pixel to turn from bright to dark and from dark to bright. The response speed of most LCD monitors is between 50ms and 100ms, but there are also a few models that can reach 30ms. The smaller the value is, the faster the response speed is, and the better the effect of displaying the video screen is.
4. Whether there is a digital interface Most LCDs used in desktop systems are designed to receive analog signals rather than digital pulse signals generated directly by the PC. This is mainly because the vast majority of standard graphics cards in the current desktop system still transmit video information from the initial digital signal to an analog signal before being transmitted to the display of the monitor. Since the LCD itself can still only process digital information, when the analog signal is received from the graphics card, the LCD needs to restore the analog signal to a digital signal and then perform processing, which will result in loss of a lot of information, resulting in deterioration of the picture quality, in order to solve the above problems. With the loss of display quality, the latest desktop LCDs have full digital interfaces. Digital products are more sophisticated, but they are more expensive and require special graphics cards with digital output interfaces.
5. Color Number Almost all LCDs currently only display high-color (256K colors), so many manufacturers use the so-called FRC (FrameRateControl) technology to display full-color images in an emulated manner. The ability of the LCD to display grayscale is also less than that of the CRT, but the eye is undetectable under normal use conditions.
6. Pixel pitch The pixel pitch of LCD displays is similar to DotPitch of CRT. The pitch of the CRT will vary depending on the mask or raster design, the type of graphics card, and the vertical or horizontal scanning frequency. The LCD monitor has a fixed number of pixels. Therefore, as long as the size and resolution are the same, the pixel pitch of all products should be the same.
7. The refresh frequency of the scan frequency LCD refers to the display frame rate, which is related to the screen scan speed and the response speed of the liquid crystal material. Since the response speed of the liquid crystal material is not very fast, even if the refresh frequency is low, the flicker is not easily perceived. Since the pixel's light-off state only changes when the screen content changes, the LCD monitor displays the screen according to the backlight and the state of the control liquid crystal. The light source of the backlight is generally a fluorescent lamp whose light frequency is about 70 kHz, which is much higher than the refresh frequency of the CRT display up to about 100 Hz. Therefore, even if the scan frequency is low, the LCD monitor screen will not have the flickering feeling like the CRT monitor, and the optimal scanning frequency is 60 Hz.
8. Resolution Due to the difference in the display principle, the LCD screen is different from the ordinary CRT monitor in that the screen resolution cannot be set arbitrarily, and generally has an optimum value. In addition to other resolutions, or can not be set, or the effect is not good. Traditional CRT monitors are more flexible for supported resolutions, but LCDs only support so-called true resolutions. Only at true resolution can the images be displayed optimally. Therefore, when selecting the LCD, make sure it supports the native resolution of the application hardware and software you are using. Do not blindly believe that the higher the resolution, the better. Keep in mind that LCD displays are different from ordinary CRT displays. If you use XGA1024x768 resolution for everyday use, you'd better make sure your LCD monitor can support the original VGA resolution, no more, no less.
1. Space-Saving Traditional Displays Due to the use of CRTs, electron beams must be emitted from the electron guns to the screen, so the tube neck cannot be made too short. When the screen size increases, the volume and weight of the entire display will be drastically increased. The TFT liquid crystal display shows through The electrode on the screen controls the state of the liquid crystal molecules to achieve the purpose of display. Even if the screen is enlarged, its volume will not increase proportionately. In general, the thickness of the LCD display, regardless of the size of the screen, is controlled within 20 cm, and The CRT display is also much lighter in weight than the same display area.
2. Energy-saving CRT displays require heating the electrode elements so that the electron gun emits electron beams at a very high speed, so we often feel that the CRT generates a lot of heat. This is also the main reason for the energy consumption of the CRT. The TFT liquid crystal display consumes only the electrodes and the driver due to the power. On the IC, therefore, the power consumption is much smaller than that of a conventional display. A 15-inch LCD monitor consumes about one quarter of the power of a 17-inch CRT monitor. Taking into account the fact that the LCD monitor can reduce air-conditioning and cooling costs, the power-saving effect is quite obvious, and the total cost of ownership of the product is reduced. Very favorable.
3. This is the greatest advantage of LCD monitors for health benefits. Traditional monitors use electron guns to emit electron beams and hit the screen with radiation. Although CRT monitors have many ways to reduce radiation, they still cannot be cured. At this point, TFT liquid crystal display has inherent advantages, it is basically called "zero radiation" products, only a small amount of electromagnetic waves from the drive circuit, because the liquid crystal display does not need to open the cooling holes, as long as the housing is sealed and can be ruled out Electromagnetic leaks. TFTLCD has no radiation, no flicker, plus soft colors, can effectively reduce the eyes of the user's fatigue, LCD can really be called a healthy display, so in some places sensitive to radiation problems, such as the stock exchange, hospitals and other units, The LCD display is widely used. With people's increasing attention to their own health and the gradual decline in the price of LCD displays, it is believed that more and more people will choose LCD displays.
4. The unique display style First of all, the LCD is a completely flat display. The liquid crystal display technology not only eliminates bulky kinescopes, but also uses a flat glass plate. It does not have any directional protrusions. It is flat and lightweight, and the LCD display is clear and soft. There is a more realistic and saturated color effect and the image quality is more accurate. Many friends like the unique display style of LCD monitors. Compared with CRT monitors, the lack of LCD monitors mainly in the following two points: 1. The display effect is not enough. Because the display screen of the conventional display uses a phosphor, the electron beam hits the phosphor and displays an image, and thus is brighter than the translucent display of the liquid crystal, and the color is more vivid, especially at the viewing angle. TFT liquid crystal displays are much better (almost no visual angle problem). In displaying the reaction speed, the traditional display is also more advantageous, with almost no delay.
2. The price is too expensive The current LCD monitor's biggest disadvantage is its price. The same size LCD is much more expensive (about 3 times) than the CRT, and it is not easily affordable by the general public.
Second, the purchase of liquid crystal display points Because LCD and CRT are completely different in the working principle, LCD display on the purchase, both similar to the ordinary CRT monitor notes, there are some special points for purchase. When purchasing an LCD monitor, it is important to first examine the special technical features that are different from ordinary CRT monitors.
1. The size of the viewing angle Due to the display principle, the LCD monitor must be viewed from the front to obtain the best visual effect. If viewed from other angles, the screen will have different degrees of dimming, color changes and other issues. The visual range refers to the clear angle range from the middle of the screen to the top, bottom, left, and right directions. The larger the value is, the more naturally the range is, but the range of the four directions is not necessarily symmetrical. In general, the viewing angle of 140 to 160 degrees should be the basic indicator of the LCD monitor. In addition, the horizontal and vertical viewing angles should preferably be the same.
2. Brightness and Contrast The higher the brightness value, the more natural the picture is. The unit of brightness is della (cd/m2). The general LCD luminance value is about 150cd/m2, and some can reach 250cd/m2 or more. At present, the brightness of TFT liquid crystal displays that can be seen in China is basically around 200cd/m2. LCD brightness has a great influence on the display. Also note that some LCD displays have uneven brightness and are very bright at the center of the screen, but at the edges, the brightness is reduced a lot and you should be careful when purchasing. The higher the contrast, the more vivid and saturated the colors, and the three-dimensional appearance. The contrast is low, the colors appear poor, and the images become non-stereoscopic. The current LCD contrast ratios vary widely from 100:1 to 300:1 or even higher. However, the contrast is not as high as possible. To achieve a good image quality, it must be matched with the brightness.
3. The reaction speed response time reflects the speed of each pixel of the liquid crystal display responding to the input signal. The smaller the value, the better. The smaller the response time is, the faster the motion picture is displayed will not make the user feel the tail drag. The unit of measurement response or recovery time is milliseconds, which is the time required for a single pixel to turn from bright to dark and from dark to bright. The response speed of most LCD monitors is between 50ms and 100ms, but there are also a few models that can reach 30ms. The smaller the value is, the faster the response speed is, and the better the effect of displaying the video screen is.
4. Whether there is a digital interface Most LCDs used in desktop systems are designed to receive analog signals rather than digital pulse signals generated directly by the PC. This is mainly because the vast majority of standard graphics cards in the current desktop system still transmit video information from the initial digital signal to an analog signal before being transmitted to the display of the monitor. Since the LCD itself can still only process digital information, when the analog signal is received from the graphics card, the LCD needs to restore the analog signal to a digital signal and then perform processing, which will result in loss of a lot of information, resulting in deterioration of the picture quality, in order to solve the above problems. With the loss of display quality, the latest desktop LCDs have full digital interfaces. Digital products are more sophisticated, but they are more expensive and require special graphics cards with digital output interfaces.
5. Color Number Almost all LCDs currently only display high-color (256K colors), so many manufacturers use the so-called FRC (FrameRateControl) technology to display full-color images in an emulated manner. The ability of the LCD to display grayscale is also less than that of the CRT, but the eye is undetectable under normal use conditions.
6. Pixel pitch The pixel pitch of LCD displays is similar to DotPitch of CRT. The pitch of the CRT will vary depending on the mask or raster design, the type of graphics card, and the vertical or horizontal scanning frequency. The LCD monitor has a fixed number of pixels. Therefore, as long as the size and resolution are the same, the pixel pitch of all products should be the same.
7. The refresh frequency of the scan frequency LCD refers to the display frame rate, which is related to the screen scan speed and the response speed of the liquid crystal material. Since the response speed of the liquid crystal material is not very fast, even if the refresh frequency is low, the flicker is not easily perceived. Since the pixel's light-off state only changes when the screen content changes, the LCD monitor displays the screen according to the backlight and the state of the control liquid crystal. The light source of the backlight is generally a fluorescent lamp whose light frequency is about 70 kHz, which is much higher than the refresh frequency of the CRT display up to about 100 Hz. Therefore, even if the scan frequency is low, the LCD monitor screen will not have the flickering feeling like the CRT monitor, and the optimal scanning frequency is 60 Hz.
8. Resolution Due to the difference in the display principle, the LCD screen is different from the ordinary CRT monitor in that the screen resolution cannot be set arbitrarily, and generally has an optimum value. In addition to other resolutions, or can not be set, or the effect is not good. Traditional CRT monitors are more flexible for supported resolutions, but LCDs only support so-called true resolutions. Only at true resolution can the images be displayed optimally. Therefore, when selecting the LCD, make sure it supports the native resolution of the application hardware and software you are using. Do not blindly believe that the higher the resolution, the better. Keep in mind that LCD displays are different from ordinary CRT displays. If you use XGA1024x768 resolution for everyday use, you'd better make sure your LCD monitor can support the original VGA resolution, no more, no less.
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