Introduction to LCD panel types

The quality of an LCD monitor depends first on its panel, because the quality of the panel directly affects the viewing effect of the picture, and the LCD TV panel accounts for more than half of the cost of the whole machine, which is the main factor affecting the cost of LCD TV. Therefore, to choose a good LCD monitor, you must first choose its panel. The LCD panel can largely determine the very important parameters of the LCD monitor, such as brightness, contrast, color, and viewing angle. The development speed of LCD panels is very fast. From the third generation in previous years, it has rapidly developed to the fourth and fifth generations, and then skipped the sixth generation to the seventh generation, and the updated eighth generation panel is also being planned. The manufacturers of LCD panels are mainly Samsung, LG-Philips, IVT, AUO, BOE, Huaxing Optoelectronics, etc. Due to the differences in the technical levels of each company, the LCD panels produced are roughly divided into several different types. Common ones are TN panels, VA panels such as MVA and PVA, IPS panels, and CPA panels.
TN panel
TN stands for Twisted Nematic panel. The low production cost makes TN the most widely used entry-level LCD panel and is widely used in mainstream mid- and low-end LCD monitors on the market. Most of the TN panels we see are improved TN+film, where film is the compensation film, which is used to make up for the lack of viewing angle of TN panels. The viewing angle of improved TN panels reaches 160°. Of course, this is the limit value measured by the manufacturer under the contrast ratio of 10:1. In fact, when the contrast ratio drops to 100:1, the image has already been distorted or even color cast.
As a 6-bit panel, the TN panel can only display 64 colors of red/green/blue, and the maximum actual color is only 262144. Through the "dithering" technology, it can obtain the ability to express more than 16 million colors. It can only display the three primary colors of 0 to 252 grayscales, so the final color display information is 16.2 M colors, not the true color 16.7M colors we usually say; plus the difficulty of improving the contrast of the TN panel is relatively large, the direct problem exposed is the thin color, poor restoration ability, and unnatural transition.
The advantage of the TN panel is that due to the small number of output grayscales, the liquid crystal molecule deflection speed is fast, and the response time is easy to improve. The LCD products below 8ms on the market basically use TN panels. In addition, Samsung has also developed a B-TN (Best-TN) panel, which is actually a modified version of the TN panel, mainly to balance the contradiction that the TN panel must sacrifice image quality for high-speed response. At the same time, the contrast can reach 700:1, which is close to the MVA or early PVA panels. Many panel manufacturers in Taiwan produce TN panels. TN panels are soft screens. If you gently scratch them with your hand, similar water marks will appear. In addition, if you look closely at the screen, it is roughly like this:
VA panel
VA panel is a type of panel that is widely used in high-end LCDs and is a wide-viewing angle panel. Compared with TN panels, the 8-bit panel can provide 16.7M colors and a large viewing angle, which is the capital of this type of panel positioning at the high end, but the price is also relatively more expensive than TN panels. VA panels can be divided into MVA panels led by Fujitsu and PVA panels developed by Samsung, of which the latter is the inheritance and improvement of the former. VA panels have the highest front (front view) contrast, but the uniformity of the screen is not good enough, and color drift often occurs. Sharp text is its killer feature, and the black and white contrast is quite high.
Fujitsu's MVA technology (Multi-domain Vertical Alignment) can be said to be the earliest wide-viewing LCD panel technology. This type of panel can provide a larger viewing angle, usually up to 170°. Through technology licensing, panel companies such as Chi Mei Electronics (Chi Jing Optoelectronics) and AU Optronics in Taiwan Province of my country have adopted this panel technology. The improved P-MVA panel has a viewing angle of 178° close to the horizontal, and the grayscale response time can reach less than 8ms. Samsung Electronics' PVA (Patterned Vertical Alignment) technology also belongs to the category of VA technology. It is the successor and developer of MVA technology. Its comprehensive quality has surpassed the latter in all aspects, and the improved S-PVA can already keep pace with P-MVA, achieving extremely wide viewing angles and faster and faster response times. PVA uses transparent ITO electrodes to replace the liquid crystal layer protrusions in MVA. The transparent electrode can obtain a better aperture ratio and minimize the waste of backlight. This mode greatly reduces the possibility of "bright spots" on the LCD panel, and its status in the era of LCD TVs is equivalent to the "long tube" in the era of picture tube TVs. Samsung's main PVA mode wide-viewing angle technology is widely adopted by Japanese and American manufacturers due to its strong production capacity and stable quality control system. PVA technology is widely used in mid-to-high-end LCD monitors or LCD TVs. VA panels are also soft screens. If you gently scratch them with your hand, similar water marks will appear. If you look closely at the screen, it looks like this:
IPS panel
IPS (In-Plane Switching) technology is a liquid crystal panel technology launched by Hitachi in 2001, commonly known as "Super TFT". The IPS camp is led by Hitachi, and brings together a number of manufacturers such as LG-Philips, HannStar Display, and IDTech (a joint venture between Chi Mei Electronics and IBM Japan), but there are not many models available on the market. The biggest feature of the IPS panel is that its two poles are on the same plane, unlike other liquid crystal modes where the electrodes are arranged in three dimensions on the upper and lower surfaces. Since the electrodes are on the same plane, the liquid crystal molecules are always parallel to the screen regardless of the state, which will reduce the aperture ratio and reduce the transmittance, so IPS applications on LCD TVs will require more backlights. In addition, there is an S-IPS panel that is a modified version of IPS
The advantages of IPS panels are high viewing angles, fast response speeds, accurate color reproduction, and low prices. However, the disadvantages are that the light leakage problem is more serious, the black purity is not enough, and it is slightly worse than PVA, so it is necessary to rely on optical film compensation to achieve better black. IPS panels are mainly produced by LG-Philips. Compared with other types of panels, the screen of IPS panel is relatively "hard". It is not easy to deform like water marks when gently scratched by hand, so it is also called hard screen. When you look closely at the screen, if you see fish-scale pixels facing left, plus a hard screen, then you can be sure that it is an IPS panel.
CPA panel
CPA (Continuous Pinwheel Alignment) mode wide viewing angle technology (soft screen), CPA mode wide viewing angle technology strictly belongs to the VA camp, and each liquid crystal molecule is arranged in a radiating flame-like arrangement toward the center electrode. Because the electric field on the pixel electrode changes continuously, this wide viewing angle mode is called "continuous flame-like arrangement" mode. CPA is promoted by Sharp, the "father of liquid crystal". It should be noted here that the ASV that Sharp has always promoted does not actually refer to a specific wide viewing angle technology. It collectively refers to products that have adopted TN+Film, VA, and CPA wide viewing angle technologies as ASV. In fact, only the CPA mode is the wide-viewing angle technology pioneered by Sharp itself, and the products of this mode are basically equivalent to MVA and PVA. In other words, Sharp-branded LCD TVs may not necessarily use CPA mode LCD panels produced by Sharp itself. They may use VA mode panels from Taiwanese manufacturers or LCD panels from other manufacturers. Sharp's CPA panels have true color reproduction, excellent viewing angles, and delicate images. They are relatively expensive, and Sharp rarely sells CPA panels to other manufacturers. CPA panels are also soft screens. If you gently scratch them with your hand, similar water patterns will appear. If you look closely at the screen, it is roughly like this:
ADSDS panel
ADSDS (Advanced Super Dimension Switch) advanced super-dimensional field switching technology (hard screen) strictly belongs to the IPS camp and is a technical improvement on traditional IPS panels. However, unlike IPS, the ADSDS panel uses ITO transparent electrodes instead of traditional metal electrodes, which increases the aperture ratio and transmittance. Combined with the liquid crystal molecule arrangement similar to the IPS panel, it can enhance the color expression of the LCD panel. ADSDS is mainly promoted by Chinese LCD panel suppliers and is mainly used in self-branded LCD TVs.
In addition, some other manufacturers also have their own LCD panel technologies, such as NEC's ExtraView technology, Panasonic's OCB technology, and modern FFS technology. These technologies are improvements on the old TFT panels, providing viewing angles and response times, and are usually only used on their own brand LCD monitors or LCD TVs. In fact, all of the above panels belong to TFT panels, but each panel has its own technology and name, so the name TFT is not often used.