TN, PVA, MVA and other panels are all soft screens, and the main representative manufacturers are Samsung and Sharp.
I. Overview
At present, there are two kinds of views on LCD TV market: "soft screen" and "hard screen". Generally speaking, hard screen refers to IPS panel (LG- Philips is the main representative manufacturer), and soft screen refers to TN, PVA, MVA and other panels (Samsung is the main representative manufacturer). Therefore, it is not very accurate to simply use "soft and hard" to distinguish the quality of LCD panels. And there are two different opinions. First, the hard screen is actually an outer screen with higher hardness outside the LCD screen. If the two screens are not pasted well, the picture quality will be affected when they expand when heated and contract when cooled, and the poor light transmission performance of the outer screen will also affect the color effect of the picture. Another way of saying it is that the cost of LCD screen accounts for the most important part of LCD TV, and it is exquisite, and the soft screen is easy to be scratched.
Second, introduce "soft screen"
The so-called soft screen is a relatively hard screen, that is, a liquid crystal panel without a protective outer film. TN, PVA, MVA and other panels are all soft screens, and the main representative manufacturer is Samsung. The outstanding feature of this screen is that when you gently press it with your fingers or touch it with your nails, there will be obvious water ripples, but they will disappear after a while and will not affect the picture quality. Perhaps it is because Samsung S-LCD and other LCD screens are easy to press out "water ripples", so they are called "soft screens".
VA type: VA type LCD panel is widely used in current display products. When used in high-end products, 16.7M color (8bit panel) and large viewing angle are its most obvious technical features. At present, VA panels are divided into MVA and PVA.
MVA type: full name (multi-domain vertical alignment), which is a multi-quadrant vertical alignment technology. It uses protrusions to make the liquid crystal stand at a certain angle instead of the traditional vertical. When the voltage is applied to make the liquid crystal molecules become horizontal to let the backlight pass through, the speed is faster, which can greatly shorten the display time, and because the protrusions change the orientation of the liquid crystal molecules, the viewing angle is wider. The viewing angle can be increased to more than 160 degrees, and the reaction time can be shortened to less than 20 ms
PVA type: It is a panel type introduced by Samsung, and it is a vertical adjustment technology for images. This technology directly changes the structure of the liquid crystal cell, greatly improves the display efficiency, and obtains better brightness output and contrast than MVA. In addition, on the basis of these two types, two improved panels, S-PVA and P-MVA, have been developed. In terms of technical development, the viewing angle can reach 170 degrees, the response time can be controlled within 20ms (accelerated to 8ms GTG through Overdrive), and the contrast can easily exceed the high level of 700: 1. Most products of Samsung's own brand are PVA LCD panels.
Third, launch a "hard screen"
Hard screen refers to IPS panel, and its LCD screen is covered with a layer of transparent plexiglass material. Its advantage is that it can protect the screen from damage and dirt to the greatest extent under the condition that the workmanship meets the standard (without distorting the picture and affecting the color effect of the picture). After all, cleaning the dirty LCD screen is more troublesome. It is much easier to clean up after adding panels, especially in families with children. Of course, hard screens naturally have some disadvantages and increases.
Type of IPS: IPS (in-plane switching) technology is a panel technology introduced by Hitachi at 200 1, which is also commonly known as "super TFT". As we know, the liquid crystal molecules of traditional LCD displays generally switch between vertical and parallel States, and MVA and PVA are improved into vertical-bidirectional inclined switching mode. The biggest difference between IPS technology and the above technology is that the liquid crystal molecules are always parallel to the screen in any state, but the rotation direction of the molecules is different in the energized/normal state-note that the rotation of MVA and PVA liquid crystal molecules belongs to spatial rotation (Z axis), while the rotation of IPS liquid crystal molecules belongs to spatial rotation.
In order to cooperate with this structure, IPS requires improving the electrodes, which are on the same side to form a plane electric field. The problems brought by this design are twofold. On the one hand, it solves the problem of perspective. On the other hand, IPS has the disadvantages of low aperture ratio (light transmittance), slow response time and difficult to improve contrast due to the large rotation angle of liquid crystal molecules.
IPS LCD panel has the advantages of large viewing angle, fine color and so on, and looks transparent, which is also a way to identify IPS LCD panel. Many Philips LCD monitors use IPS panels. S-IPS is the second generation IPS technology, which introduces some new technologies to improve the gray inversion phenomenon of IPS mode at some specific angles. Independent panel manufacturers of LG and Philips are also LCD panels featuring ips technology.
IPS panel is a planar conversion internal structure, and liquid crystal molecules react quickly to reduce motion blur. However, the limitation of liquid crystal molecules in VA panel leads to slow response time.
The biggest feature of IPS panel is that its two poles are on the same plane, unlike other liquid crystal mode electrodes which are arranged vertically. Because the electrodes are on the same plane, liquid crystal molecules are parallel to the screen in any state, which will reduce the aperture ratio and light transmittance, so IPS applications in LCD TVs will need more backlights. In addition, there is also an S-IPS panel, which belongs to the improved IPS.
The advantages of IPS panel are high viewing angle, fast response, accurate color reproduction and low price. However, the disadvantage is that the light leakage problem is serious, and the purity of black is not enough, which is slightly worse than PVA. It is necessary to rely on the compensation of optical film to achieve better black. At present, IPS panels are mainly produced by LG- Philips. Compared with other types of panels, the screen of IPS panel is more "hard", and it is not easy to be deformed by water lines when swiping by hand, so it is also called hard screen.
Fourth, the difference and connection between hard screen and soft screen
The fundamental difference between hard screen and soft screen lies in whether the screen is coated, which will not and cannot change the inherent physical properties of the LCD panel itself, so it still maintains its inherent characteristics in image quality. If on the same occasion, the image quality of LCD TVs with soft and hard screens is obviously different by using the same signal source, then the most critical issue should be the core configuration such as the level of LCD panel and IC driving performance, rather than the difference between "hard screen" and "soft screen".
Hard screen and soft screen are well distinguished: lightly stroke the screen by hand, if there is obvious water mark, it belongs to soft screen; If the watermark is weak or even absent, it is a hard screen. Up to now, there are no words "soft" and "hard" in many domestic and foreign standards on LCD screen quality, and no authoritative organization has commented on the advantages and disadvantages of hard screen and soft screen. Therefore, it can be said that hard screen and soft screen are only the difference of LCD panel post-processing, and there is no essential difference between good and bad. More precisely, the hard screen is only the protective film on the LCD panel. LCD TVs with coated screens are not necessarily excellent, and LCD TVs without coated screens are not necessarily bad.
As we all know, although the screen is the key component of LCD TV, the application of control circuit and audio-visual optimization technology is also very important. An excellent LCD TV should be A-class LCD panel+excellent control circuit and audio-visual optimization technology, and the image quality performance of LCD TV must be a comprehensive embodiment of the technical characteristics of LCD panel, control circuit and image optimization technology. Therefore, it is biased and meaningless to judge the pros and cons only by "soft" and "hard".
As far as the material of LCD screen is concerned, both hard screen and soft screen are the same physical structure of LCD, and their basic performance is the same. However, the safety of hard screen with protective film seems to be improved, but it still won't surpass the fragile physical defects of LCD screen. Therefore, whether it is a hard screen LCD TV or a soft screen LCD TV, it is also afraid of collision and needs careful protection. As long as the user is careful not to be hit by gravity or scratched by sharp objects, the screen will not be damaged.
Verb (abbreviation of verb) The Debate between "Soft Screen" and "Hard Screen"
At present, there are two kinds of views on LCD TV market: "soft screen" and "hard screen". Generally speaking, hard screen refers to IPS panel (LG- Philips is the main representative manufacturer), and soft screen refers to TN, PVA, MVA and other panels (Samsung is the main representative manufacturer). Therefore, it is not very accurate to simply use "soft and hard" to distinguish the quality of LCD panels. And there are two different opinions. First, the hard screen is actually an outer screen with higher hardness outside the LCD screen. If the two screens are not pasted well, the picture quality will be affected when they expand when heated and contract when cooled, and the poor light transmission performance of the outer screen will also affect the color effect of the picture. Another way of saying it is that the cost of LCD screen accounts for the most important part of LCD TV, and it is exquisite, and the soft screen is easy to be scratched.
At present, there are indeed some LCD panels with hard materials such as glass or resin added outside to prevent ordinary LCD screens from being scratched. However, from the current production level, there is no obvious difference in quality between the so-called hard screen and soft screen. The protective film added to the hard screen will not cause poor light transmission, and the bonding process between the film and the screen is also quite elegant. Soft screens without protective outer film are generally not easy to be scratched as long as consumers pay attention when using them, without gravity impact and scratching by sharp objects. Therefore, the choice of LCD should not only look at the hardness of the screen, but also look at the brand and quality.
The technical service personnel of the production enterprises almost unanimously said that LCD TV production enterprises have no distinction between soft screen and hard screen, and the so-called soft screen and hard screen have no distinction between good and bad quality, which is completely added by promoters when introducing products in the market.
Chen Qiliang, director of the Liquid Crystal Branch of the Chinese Physical Society, said that the so-called soft screen and hard screen in the market do have some technical reasons. At present, some LCD panel manufacturers do add hard materials such as glass or resin outside the LCD screen to prevent the ordinary LCD screen from being scratched. However, from the current production level, there is no obvious difference in quality between the so-called hard screen and soft screen. The protective film added to the hard screen will not cause poor light transmission, and the bonding process between the film and the screen is also quite elegant. Soft screens without protective outer film are generally not easy to be scratched as long as consumers pay attention when using them, without gravity impact and scratching by sharp objects. He reminded that when consumers buy LCD TVs, well-known LCD TV manufacturers often use high-quality LCD screens, and it is more important to choose brands and after-sales service.