What is the professional knowledge of LCD module and LCD module

What is an LCD module

The LCD module is simply a screen + backlight assembly.
The display part of the LCD TV is the liquid crystal module, and its low temperature is equivalent to the picture tube in the CRT.
Other parts include the power supply circuit, signal processing circuit, etc., and of course the casing.
The module is mainly divided into screen and backlight components. The two parts are assembled together, but they work independently of each other (ie, the circuits are not related).
The principle of the liquid crystal display is that the backlight assembly emits uniform surface light, and the light reaches our eyes through the LCD screen. The function of the screen is to process the light by pixels to display images. Both parts contain a lot of parts, so I won't go into details here. Currently, the best technology is Sharp, followed by Samsung and Sony.

LCD panel expertise

Usually when we sell LCDs, there are always consumers who ask what level your screen is, everyone may casually say it is A-level, A + -level, in fact, such answers are not professional, if the consumer is professional Of consumers who talked to such sales with disdain, will only go away, if the tenth of the transactions can be completed, the customer has already understood the outside market, and it is just to let you out. At the lowest price, we must be a valuable salesman for LCD sales. Blind low-cost shipments are not excellent salesmen. You only need to convince customers, let customers believe your profession, and your service. success!

For conventional panel grading standards, please see: LCD panel grading standards, truly professional panel grading factory standards, see: AU panel grading standards

If you want to be a professional LCD salesman, you must have a deep understanding of LCD professional terms. You know more than customers. At least you can't understand the nouns that customers can't say. Below are some of my collection. LCD proper nouns, you can combine the models you sell to understand:
LCD panel

The liquid crystal panel is the main component of the liquid crystal display, accounting for nearly 80% of the cost of the liquid crystal display. At present, there are not many manufacturers with panel manufacturing technology in the world, only SHARP (Sharp), SANYO (Sanyo), Samsung, LG-Philips, Taiwan ’s AUO and other manufacturers have core technology, most LCD displays use their panels To assemble and produce.

Ant's experience: We can prove that we encountered some in the sale, the LCD panel was artificially damaged after the sale and changed the screen, the after-sales customer service of the major manufacturers answered (LCD screen + manual replacement of the screen) the charging standard was close to or exceeded a new LCD Cost, let customers understand the importance of LCD screen quality and the importance of three-year free service! Not long ago, we encountered a couple fighting in Danjiangkou, broke the screen, and wanted to change the screen, and the manufacturer's customer service answer was artificial If it is damaged, the charge will be 1,000 yuan. It is recommended that the customer not repair it, sell the circuit board and buy a new one. There is also the example of many customers who have been selling "Stupid Q" brand LCDs for four years before, after using them for one year, the screen is not bright, black, and the lamp glows yellow. Their customer service refuses to repair. Last week we encountered a gray shadow on the VA721 screen of a customer in Ezhou. Because it was free for three years, it was replaced with a new screen for free.

The quality and value of the panel are currently divided into three grades: Sanyo and Sharp of Piglet belong to the first grade, which are mostly used in high-end products, such as: EIZO, SONY, ViewSonic (VP, VG series), etc., the price is relatively high; South Korea's Samsung, LG, and Philips belong to the second level, and most of them are used on monitors sold with branded machines; Taiwanese manufacturers such as AUO are in the third position. Chimei and Hanyu Caijing mostly obtain a large number of OEM OEM orders at a cost-effective ratio. According to my understanding, there is also a NEC-SVA (Shanghai Broadcasting and TV) joint venture fifth-generation line panel with particularly good prices. We can see ultra-low prices in the market. Most price models are such panels.

Dead pixels

The so-called dead pixels are the general term for pixels that cannot be displayed normally on the LCD panel. The liquid crystal panel is composed of many display points, which are completed by the liquid crystal substance on each display point under the control of electric signals to change the light transmission in the same state. At a resolution of 1024 × 768, the LCD panel has a total of 786,432 display points, so many points are difficult to completely guarantee that individual problems will occur. However, at the current level of technology, if the LCD panel with dead pixels is scrapped, it is believed that the LCD display can only be a sky-high commodity in the window. Therefore, the number of dead pixels has become the main basis for panel classification. Manufacturers generally avoid LCD panels by splitting the bad spots, and sell LCD panels with no or few bad spots at a higher price, while those with a larger number of bad spots are sold to small factories at low prices to produce cheap products.

The current main grading standards are:

Panel manufacturer standards: Korean manufacturers, 3 or less are A-level Japanese manufacturers, 5 or less are A-level Taiwan manufacturers, and 8 or less are A-level manufacturers

Key indicators of mainstream LCD monitor brands:

AA level: The LCD display without any dead pixels is AA level.
Class A: Less than 3 dead pixels, with no more than one bright spot, and the bright spot is not in the central area of ​​the screen.
Level B: Less than 3 dead pixels, of which there are no more than two bright spots, and the bright spots are not in the central area of ​​the screen.

Ant Tip: The LCD panel has so far not been able to overcome the dead spots and highlights from the process, the general ratio of a little bit to no point is 8: 2; we see the no-bad spot guarantee promised by the dealers, most of them are manufacturers and distribution Some of the products in the business are picked manually, and there is no point to promise to sell to the seller at a high price, while some are sold to the industry order at a low price. Therefore, if you find this model, you should talk to the salesperson and customers. Can meet the requirements of users to pick points, of course, the price should also be controlled, some machines should be cheap (or send gifts) as soon as possible to the Internet cafes and unit customers!


The accessories such as control IC, filter and orientation film used in the manufacture of LCD panels are related to the contrast of the panel. For the average user, a contrast ratio of 350: 1 is enough, but in the professional field, such contrast is not enough. Meet the needs of users. Compared with CRT monitors, it is easy to achieve a contrast ratio of 500: 1 or higher. Only high-end LCD monitors can achieve this level, because contrast is difficult to accurately measure by the instrument, so you have to see it yourself when picking.

Little Ant Tip: Contrast is very important, it can be said that it is a more important indicator to select the LCD than the bright spot. When you understand that the LCD that your customers buy is used for entertainment and watching DVDs, you can emphasize that the contrast is more important than no dead pixels. When we look at streaming media, the general source of the film is not very bright, but to see the contrast between the light and dark of the character scene, the texture of the hair from gray to black, it depends on the level of contrast. ViewSonic's VG and VX have always emphasized the contrast index. The VG910S is a 1000: 1 contrast ratio. We compared this with a Samsung dual-head graphics card. The Samsung LCD is obviously comparable. You can try it if you are interested. In the 256-level grayscale test in the test software, you can see more small gray grids when you look up, that is, good contrast!


Liquid crystal is a substance between solid and liquid, which cannot emit light by itself. It needs an additional light source. Therefore, the number of lamps is related to the brightness of the LCD. The earliest LCD monitors only had two lamps on the top and bottom. Up to now, the lowest for popular models is four lamps, and the highest is six lamps. The four-lamp design is divided into three placement forms: one is that there is a lamp on each of the four sides, but the disadvantage is that there will be a black shadow in the middle, and the solution is to arrange the four lamps from top to bottom, The last one is the "U" -shaped display, which is actually two lamps produced by the two lamps in disguise. The six-lamp design actually uses three lamps. The manufacturer bends the three lamps into a "U" shape and places them in parallel to achieve the effect of six lamps.

Little ant tips: Brightness is also an important indicator. The brighter the LCD, the better it looks from a row of LCD walls. The high-brightness technology we often see in CRT (Sonic is called Gaoliang, Philips It ’s called Xianliang, BenQ is called Ruicai.) It is by increasing the current of the shadow mask tube and bombarding the phosphor to produce a brighter effect. Such a technology is generally traded for sacrificing image quality and the life of the display. All Products using this kind of technology are normally bright by default, and they can only be executed by pressing a button. Press 3X to play the game; press again to change to 5X to watch the disc, and he will become confused when he looks at it. To see the text, you have to honestly return to the ordinary text mode, this design is actually to let everyone not use highlighting. The principle of LCD display brightness is different from CRT. They are realized by the brightness of the backlight tube behind the panel. Therefore, the design of the lamp tube is more, the light will be uniform. In the early days, when we sold LCDs, we told others that LCDs were three, so it was a good thing. But at the time, Chi Mei CRV came up with a six-lamp technology. In fact, the three tubes were bent into a "U" shape and became The so-called six lamps; such a six-lamp design, plus the lamp itself is very strong, the panel will see very bright, such a masterpiece is represented by VA712 in ViewSonic; but all the highlighted panels will have a fatal Injury, the screen will leak light. This term is rarely mentioned by most people. I personally think that he is very important. Light leakage refers to the liquid crystal is not black, but white and gray under a completely black screen. Therefore, a good LCD should not just emphasize the brightness, but to emphasize the contrast. ViewSonic's VP and VG series are products that do not talk about brightness and contrast!

Signal response time

Response time refers to the response speed of the LCD to the input signal, that is, the response time of the liquid crystal from dark to bright or from bright to dark, usually in milliseconds (ms). To make this clear, we need to start with the human eye's perception of dynamic images. There is a "visual residue" phenomenon in the human eye, and the high-speed motion picture will form a short impression in the human brain. Animation, movies, etc. until now the latest game is the application of the principle of visual residue, allowing a series of gradual images to be displayed quickly and continuously in front of the human eye, forming a dynamic image. The acceptable screen display speed is generally 24 frames per second, which is the origin of the 24 frames per second of the movie. If the display speed is lower than this standard, people will obviously feel the pause and discomfort of the screen. According to this index calculation, the display time of each screen needs to be less than 40ms. In this way, for a liquid crystal display, a response time of 40ms becomes a hurdle, and a display of less than 40ms will have a significant "tailing" or "afterimage" phenomenon, which makes people feel chaotic. If you want the image to be smooth, you need to reach 60 frames per second.

I used a very simple method to calculate the number of frames per second under the corresponding reaction time as follows:

Response time 30ms = 1 / 0.030 = approximately 33 frames per second response time 25ms = 1 / 0.025 = approximately 40 frames per second response time 16ms = 1 / 0.016 = approximately 63 frames per second response time 12ms = 1 /0.012=approximately 83 frames per second response time 8ms = 1 / 0.008 = approximately 125 frames per second response time 4ms = 1 / 0.004 = approximately 250 frames per second response time 3ms = 1 / 0.003 = seconds Approx. 333 frames response time 2ms = 1 / 0.002 = approx. 500 frames per second response time 1ms = 1 / 0.001 = approx. 1000 frames per second

Little Ant Tip: Through the above content we have learned the relationship between response time and the number of frames. From this point of view, the shorter the response time, the better. At the time, when the LCD market was launched, the lowest response time was 35ms, which was mainly represented by EIZO. Later, BenQ ’s FP series came out at 25ms, and basically could n’t feel it from 33 to 40 frames. The change is 16MS, which displays 63 frames per second to meet the requirements of movies and general games, so until now 16MS is not outdated. With the improvement of panel technology, BenQ and ViewSonic have started a speed battle. ViewSonic starts from 8MS, 4 milliseconds has been released to 1MS, it can be said that 1MS is the end of the LCD speed battle. For game enthusiasts, the speed of 1MS means that the marksmanship of CS will be more accurate, at least psychologically, such customers will recommend VX series monitors. But everyone should pay attention to the grayscale response when selling. The difference between the full-color response text and sometimes the grayscale 8MS and full-color 5MS mean the same thing. Just like when we sold CRT before, we said that the dot distance is .28 It must be said that his is .21, but the horizontal dot pitch is ignored. In fact, the two sides are talking about one meaning. Now LG has recently come up with a sharpness of 1600: 1. This is also a concept hype. Everyone uses Basically, there are only a few screens, and how can only LG be able to achieve 1600: 1, and everyone stays at the level of 450: 1? Speaking of consumers, the meaning of sharpness and contrast is clearly broken. It is like the PR value of AMD, which has no real meaning.

Viewing angle

The viewing angle of the liquid crystal is a headache. When the backlight passes through the polarizer, liquid crystal and alignment layer, the output light has directionality. That is to say, most of the light is emitted vertically from the screen, so when viewing the LCD from a large angle, you can not see the original color, or even see all white or all black. In order to solve this problem, manufacturers have also started to develop wide-angle technology, so far there are three more popular technologies, namely: TN + FILM, IPS (IN-PLANE -SWITCHING) and MVA (MULTI-DOMAIN VERTICAL alignment).

TN + FILM technology is to add a layer of wide viewing angle compensation film on the original basis. This layer of compensation film can increase the viewing angle to about 150 degrees, is a simple and easy method, and is widely used in liquid crystal displays. However, this technology does not improve performance such as contrast and response time. Perhaps TN + FILM is not the best solution for manufacturers, but it is indeed the cheapest solution, so most Taiwanese manufacturers use this kind of technology. Method to build a 15-inch LCD display.

IPS (IN-PLANE -SWITCHING, in-board switching) technology, which claims to allow the viewing angle of up, down, left and right to reach a greater 170 degrees. Although the IPS technology increases the viewing angle, using two electrodes to drive the liquid crystal molecules requires greater power consumption, which increases the power consumption of the liquid crystal display. In addition, fatally, the response time of driving liquid crystal molecules in this way will be relatively slow.

MVA (MULTI-DOMAIN VERTICAL alignment) technology, the principle is to add protrusions to form multiple viewing areas. The liquid crystal molecules are not completely vertically aligned when they are static. The liquid crystal molecules are aligned horizontally after the voltage is applied so that light can pass through the layers. MVA technology increases the viewing angle to more than 160 degrees, and provides a shorter response time than IPS and TN + FILM. This technology was developed by Fujitsu, and currently Chimei Taiwan (Qili is a subsidiary of Chimei in mainland China) and Taiwan AUO are authorized to use this technology. ViewSonic ’s VX2025WM is a masterpiece of this type of panel. The horizontal and vertical viewing angles are both 175 degrees. There is basically no visual dead angle, and it also promises no bright spots. The viewing angles are divided into parallel and vertical viewing angles. The vertical central axis of the center is the center, moving left and right, you can clearly see the angle range of the image. The vertical angle is centered on the parallel central axis of the display screen and moves up and down to clearly see the angle range of the image. The viewing angle is in "degrees". At present, the most common form of labeling is to directly mark the total horizontal and vertical range, such as: 150/120 degrees. The current minimum viewing angle is 120/100 degrees (horizontal / vertical). Below this value is unacceptable, it is best to reach 150/120 degrees or more.

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