Everyone should understand that compared with the desktop LCD display, the screen of the notebook computer is special. Because of its non-upgradeability, it is decided that consumers have higher expectations for the performance of the screen when purchasing. On the other hand, due to the overall notebook Volume and power consumption limits (except for some BT-class desktop replacement books), not all advanced display technologies can be applied to laptop screens. From the type of notebook screens, most notebooks currently use ordinary screens. Both with mirrored screens. Ordinary screens use anti-glare technology, but this anti-glare technology often causes the light emitted from the liquid crystal panel to be dispersed, resulting in a lack of sharpness in the display. The mirror screen is mainly anti-reflection technology. Anti-reflection technology mainly deposits a metal film on the surface of the polarizing film, and uses the principle of light interference to reduce the reflection value and reduce the reflection to less than 1%. Since the anti-glare technology is not used, and the reflective metal film is added to make the display more sharp, the anti-reflection technology can also improve the viewing angle of the screen. In addition, widescreen, high brightness, large viewing angle, etc. are similar to the desktop LCD. The word is also applicable to the screen of the notebook, and the notebooks that are in the mainstream position in the current market have improved in these applications, but they are far from meeting the requirements of people. They often hear people saying that their screens are leaking and the viewing angle is too Small and other words. Problems such as brightness, contrast, color, and viewing angle are not a good solution on current mainstream notebook screens. Although there are many technologies such as layer improvement and lamp improvement, many manufacturers have introduced their own notebook-specific technologies (such as Toshiba Clear Super View technology, ASUS enamel display enhancement technology), but they are currently notebooks. On the screen's material specifications, manufacturing processes, processing methods, and other issues, these technologies are just around the corner, and the lifting effect is not obvious.
Widescreen can get a good visual effect, but the power consumption can not be ignored, and the LCD screen is indeed a big burden in terms of the mobility that the notebook is most concerned about. On the one hand, the current power consumption of LCD screens is relatively large, so in order to extend the use time, many users adjust the brightness of the notebook screen to very dark when using battery life; on the other hand, its volume also affects the entire notebook. A factor in computer portability. In the future, the goal of notebook screens will undoubtedly be lighter and thinner, more power-efficient, and better, so can you achieve this goal through the technology that is about to mature?
OLED and white LED technology
Organic Light-Emitting Diode (OLED) is not the latest product, but its application to display technology is indeed an innovation. OLED is considered to be a hotspot for future portable device displays. Currently, there are very few notebook computers on the market that have applied this technology.
Displays using OLED technology can be made very small, even small enough to be placed on the nail. The OLED emits light through an organic film driven by a current, which can be a single color such as red, green, or blue, and can even achieve a full color effect. Its advantages are low manufacturing cost, self-illumination, viewing angle of 165 ≤ or more, fast response, low power consumption, etc., which are not available in LCD.
If you've seen laptop manufacturers' open-air products, you'll be impressed: almost all laptop screens are eclipsed by strong sunlight, and the display is very blurry. The screen using OLED technology can completely avoid this situation. The OLED is self-illuminating after being powered, and the display effect is naturally clearer and softer than that of the liquid crystal display. The picture is still clear under the sunlight, so it is suitable for the outdoor use of the notebook computer. Similarly, since the viewing angle is wide, there is no problem that the LCD cannot be seen clearly from the side, and the residual image of the LCD image and the jitter of the screen are effectively avoided.
After eliminating the backlight module device, the OLED also has excellent performance in terms of power consumption and thickness. It is important to know that power control of mobile products is critical in the current situation where battery technology is not achieving rapid growth. If you use an OLED display, its ultra-low power consumption can make most notebooks last longer than the current level, which is quite attractive.
At present, the application of OLED is limited to small-size LCD screens, but SONY has achieved a certain degree of technological breakthrough. Taking the new VAIO TX as an example, the 11.1-inch screen uses white LED technology (LED backlight display), which can be called an improved OLED. There is HP's 2510P.
Today's technological advances have overcome the drawbacks of white LEDs that have much lower luminous efficiency than fluorescent tubes, ensuring that the white LEDs used today have excellent luminous efficiency, no less than fluorescent tubes. Since the white LED is much smaller than the OLED fluorescent tube, the manufacturer no longer has to reserve the conventional space for accommodating the fluorescent tube, so a lighter and slimmer configuration can be realized, which is applied to the VAIO TX. The white LED is only 0.6 mm thick, compared to a fluorescent tube with a thickness of 2 mm. At this point, the white LED is thinner than the fluorescent tube device by 1 mm, and the power consumption is well controlled.
The thinner glass surface also enhances the strength of the liquid crystal. A common misconception is that thinner glass is more susceptible to breakage. But the fact is that the thinner the glass, the more malleable it means, the more flexible it is, and therefore the thinner glass actually has greater resistance to breakage.
What is LED backlight technology
As we all know, due to the special structure of the notebook, it is destined that its screen can not be very large, so most of the notebooks we have seen are TFT LCD materials. The LCD panel itself is only responsible for the image generation, and the brightness is projected on the LCD screen by means of a backlight tube. It can be said that the LCD display is the core of the notebook, the highest cost, and one of the most power-consuming components. As mentioned above, although the widely used TFT LCD screen technology is quite mature, it has some inherent defects such as narrow color gamut, low energy utilization, high power consumption and short life. In fact, these have a lot to do with its CCFL (Cold Cathode Fluorescent Lamps) backlight technology. In order to solve these problems, people have been looking for alternative technologies and products. In the process, LED backlight technology has been incorporated into our eyes. A number of notebook products using this technology have emerged.
Ignition cold cathode fluorescent tube
Compared with CCFL, LED backlights can provide stable and continuous work for notebooks, including smaller lamp volume, less power consumption, and absolutely no toxic substances (such as mercury), in order to achieve CCFL, etc. Bright requirements, a 12-inch notebook screen must be distributed at least 45 LED tubes, even if its energy consumption is much lower than CCFL. So what exactly is LED backlight technology?
LED light-emitting diode
LED backlight technology is applied to the display screen, which is a liquid crystal panel using LED (Light Emitting Diode) as a backlight module. LED (Light Emitting Diode), a solid-state semiconductor device that converts electricity directly into light. The heart of the LED is a semiconductor wafer. One end of the wafer is attached to a holder, one end is the negative pole, and the other end is connected to the positive pole of the power supply, so that the entire wafer is encapsulated by epoxy resin. The semiconductor wafer consists of two parts, one part is a P-type semiconductor, in which the hole dominates, and the other end is an N-type semiconductor, which is mainly electrons here. But when the two semiconductors are connected, they form a PN junction. When a current is applied to the wafer through the wire, the electrons are pushed toward the P region. In the P region, electrons recombine with the holes, and then the energy is emitted in the form of photons. This is the principle of LED illumination. The wavelength of light, which is the color of light, is determined by the material that forms the PN junction.
LED backlight screen lighting principle
The so-called LED (Light Emitting Diode) is also known as the light-emitting diode, which has been used for a long time, such as billboards on the roadside, various color indicators on household appliances, flashlights and backlighting on the keyboard of mobile phones. And so on have used LED as a light source. The application of LED in our real life can be seen everywhere, but it should be regarded as an emerging technology in its display products, especially in notebook products.
From the principle of luminescence, LED is made of several layers of very thin doped semiconductor materials, one layer with excess electrons, and the other layer lacks electrons to form positively charged "holes". The electrons and holes are combined with each other, and the excess energy is released in the form of light radiation. The LED is based on such a principle to realize the conversion of electro-optical light. According to the physical properties of the semiconductor material, the LED can emit different from ultraviolet to infrared. The light of different colors under the spectrum, especially the technical problem that the LED can not emit white light, lays a foundation for the application of LED in the display field.
LED backlight screen three advantages
LEDs, which are the next-generation backlights for LCD display devices, have many advantages such as high brightness, wide color gamut, fast response, independent switching, and no harmful substances such as mercury. However, in summary, the LCD LCD panel with LED as the backlight and LCD with CCFL (Cold Cathode Fluorescent Lamp) as the light source have the biggest advantages mainly reflected in the following three points:
First, the thickness of the LCD with LED backlight will be further reduced, and the notebook will be lighter.
The LED backlight is composed of a plurality of grid-like semiconductors, each of which has an LED semiconductor, so that the LED backlight successfully realizes the planarization of the light source. The planarized light source not only has excellent brightness uniformity, but also does not require complicated optical path design, so that the thickness of the LCD can be made thinner, and at the same time, it has higher reliability and stability. A thinner LCD panel means that the notebook has a lighter body weight and better mobility. For example, SONY's VAIO TX notebook uses an LED-backlit LCD display with a thickness of only 4.5mm. The thickness of the LED screen notebook panel is about 1/2 of the thickness of a regular CCFL screen pen.
Second, longer life, lower power consumption, and more environmentally friendly
The data shows that the LCD is about 30% of the total energy consumption of the notebook computer, and the LED backlight system can greatly reduce the energy consumption. It saves 48% of power compared to the usual CCFL LCD. Moreover, LED does not use elemental mercury, which is harmful to the environment, and is quite environmentally friendly, while the CCFL contains mercury. LEDs are very environmentally friendly.
Another advantage of LED is that it has a service life of up to 100,000 hours. Even if it is used continuously for 10 hours a day, it can last for 27 years. Take the TX series from Sony as an example. Compared with the VAIO T series using CCFT LCD, the thickness has been reduced from 9mm to 4.5mm, and the weight has been reduced by 26%, which has extended the battery life of one hour and more than doubled. Screen pressure resistance. Since the traditional LCD lamp needs to increase the power supply voltage to 530V, the lamp can work normally, and the screen with LED technology can work normally as long as the voltage of 40V, so that the power can be used more efficiently, reaching 9 hours of super Long battery life.
Third, the color performance of LED backlight screen is far better than CCFL
The higher refresh rate makes the LED have better performance in video. The single element of the LED display has a response speed of 1000 times that of the LCD screen. It can also be taken under strong light and is suitable for low temperature of minus 40 degrees. . The RGB LED light source can greatly enhance the color expression. On the other hand, the original CCFL backlight performs poorly in terms of color gradation due to problems such as color purity. This results in the LCD being inferior to the CRT in terms of grayscale and color transitions. According to tests, CCFL backlights can only achieve 78% of the NTSC color area, while LED backlights can easily achieve more than 100% NTSC color areas. LED backlighting also has significant advantages in terms of color expression and tone transition.
LED deficiency and summary
Even the best products are also shortcomings. The use of LED screens is not only a problem of high cost, but also some problems in the display technology in the current technical conditions. The main problem is that the maximum brightness of the screen is not high, and it may require external light source to assist illumination in a weak environment. Of course, LEDs may get better development in 2007. On the one hand, the production capacity is constantly expanding. On the other hand, various manufacturers are beginning to prepare for the screen. But perhaps the OLED screen introduced earlier will become the focus of our attention. It has more points of view than the LED screen, but now it is too early for the OLED application to be on the notebook.
In addition, although LED backlight technology has many advantages, it still needs a long period of technological development. Except for the artificial cost of LED manufacturing, which is too high in manufacturing costs. LED backlight technology also has the problem of low luminous efficiency. At present, the luminous efficiency of CCFL cold cathode fluorescent lamps can reach 50-100lm/W (lumens/Watt), while the luminous efficiency of white LED devices is only 20lm/W or even at the beginning. low. Fortunately, the technology in this field is progressing very rapidly. The luminous efficiency of white LEDs is increasing by 60% per year. So far, the luminous efficiency of white LED devices has exceeded 50lm/W and has begun to reach practical levels. This year, the luminous efficiency of white LEDs is expected to increase to a high level of 75 lm / W, coupled with the latest color correction system can also control the deviation of color and brightness within a reasonable range.
From the perspective of this series of technology and application characteristics, LED backlight technology products do have the advantages and reasons to replace the traditional LCD display technology products. It is believed that as the enthusiasm of LED manufacturers for LED backlight technology continues to rise, some shortcomings of LED will soon be resolved. At that time, the LCD panel will achieve better performance with the help of LED backlight technology. It is believed that the application of LED screens will become more and more popular in the next two years. For notebook products alone, the wide application is no longer a problem. Let us look forward to the early completion of the LED technology revolution.
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