When we watch the advertisements for LCD monitors, we seem to have understood some of the terms mentioned above, while the merchants play with these words, so that our eyes are spent before seeing the wonderful pictures of the monitors.
Then let's access the LCD parameters one by one.
liquid crystal panel
At present, most liquid crystal displays on the market belong to TFT liquid crystal panels. There are not many manufacturers in the world who have the core technology of panel production and can mass-produce panels. Famous ones include Sharp, Sanyo, Samsung, LG- Philips and AUO of Taiwan Province. Most other manufacturers buy their panels and assemble them.
However, these panels are also graded. At present, they are divided into three grades: Sanyo and Sharp from Japan belong to the first grade, and Sharp is the "father of LCD", which is mostly used in high-end products, and the natural price is also the most expensive; Samsung and LG- Philips from South Korea belong to Grade II, and most of them are used in the displays of Samsung, LG and Philips. AUO and others in Taiwan Province Province belong to the third level.
When you choose an LCD, you must see the brand of the LCD panel clearly, so as to fundamentally give the LCD a new positioning.
contrast
The brightness difference between light and dark is called contrast. With the improvement of contrast, the restored color of the display will be brighter, the layering of the picture color will be more vivid, and the color gradation transition will be more delicate.
Many components used in LCD panels have certain effects on contrast, such as control IC, color filter and even orientation film. Only the appropriate contrast can make the LCD display present ideal gray scale and color scale, so as to achieve full and rich image effects.
The contrast acceptable to human eyes is generally around 250: 1. The experience of daily use tells us that in most cases, the contrast can reach 350: 1, which is very satisfactory. CRT monitors can easily reach 500: 1 or even higher. However, with the development of technology, some high contrast liquid crystals have been introduced, such as Maya's V500, which has reached 500: 1. At present, the contrast ratio of popular liquid crystals is basically above 300: 1.
Because the contrast is difficult to measure accurately with instruments, you should look at it yourself when you pick it and feel comfortable.
clever
The higher the brightness, the clearer the display effect of the image and the more details you can see.
At present, the brightness of popular LCD is generally 250cd/㎡ (lumen). The display below this brightness is terrible, and we need to see it ourselves to know the brightness. For example, using some dark scenes in CS or other games to test, you can know whether it is good or bad at a glance.
fluorescent lamp
Liquid crystal is a kind of substance between solid and liquid, so liquid crystal itself can't emit light, and it needs an extra light source.
The earliest LCD only had two lights. Up to now, the lowest-end Volkswagen LCD is four lights, and the high-end LCD is six lights.
There are three kinds of four-lamp designs: one is four lamps on each side, the other is four lamps arranged in parallel up and down, and the other is two lamps produced in disguised form. Its design is to arrange the lights in a "U" shape.
The six-lamp design actually uses three lamps, and the manufacturer bends all three lamps into a "U" shape and then places them in parallel, so it looks as if they are composed of six lamps.
The arrangement of lamps and lanterns will affect the brightness uniformity of the screen, so you must make clear the arrangement of lamps and lanterns when you buy.
Response time
Response time refers to the response speed of LCD to input signal, that is, the response time of LCD from dark to bright or from bright to dark, which is usually calculated in milliseconds (ms). Generally speaking, the response time is divided into two parts-rising (rising time) and falling (falling time), and what we call the response time is the sum of the two.
Basically, the shorter response time, the better. The shorter the response time, the less likely the user is to see the moving image. Because according to the physiological characteristics of human eyes, if the response time exceeds 40 milliseconds (< 1000 ÷ 40 = 25 frames/second), there will be a hysteresis phenomenon of moving images.
At present, the acceptable range of the lowest response time in the market is 30ms, which is also a sign that there are more and more liquid crystal displays. Even 30 ms (1000 ÷ 30 = 33.3 frames/second) will cause tailing, but it is still a common parameter at present. Some better panels can reach 25ms or 20ms, or even higher16 ms (1000 ÷/).
Some businesses only write the rising time in their advertisements. When people see such a low value, they don't care what it is, so they must see clearly what the name of the marked value is.
Bad opinion
The liquid crystal panel is composed of a plurality of display points, and the liquid crystal material on each display point changes the refractive index of light to form an image under the control of an electrical signal. At the resolution of 1024×768, a LCD panel has 786,432 display points, so it is difficult to completely guarantee that there are no bad points.
If all LCD panels with bad spots are scrapped, it will cost a lot of money, so manufacturers generally avoid bad spots to divide LCD panels. LCD panels with no or fewer bad spots are sold to well-known brand machine manufacturers at higher prices, while those with more bad spots are generally sold to small manufacturers to produce cheap machines at low prices and dumped on the market at low prices.
Due to the different standards for defining the grade of bad spots around the world, products with the same grade A have appeared, but the number of bad spots is quite different. For example, Japanese standards with less than 3 bad reviews are classified as Grade A qualified, Korean standards with less than 5 bad reviews are classified as Grade A qualified, and Taiwan Province standards with less than 8 bad reviews are classified as Grade A qualified. At this point, we need to see clearly the origin of the LCD panel, and then judge what its grade can tell us.
Manufacturers may tell us in advertisements that their products are "three bad spots", "no bright spots", "no dark spots" and "no bad spots". What does all this mean?
Let's look at the "three bad points" first. It is better to control the bad points within three. The "bad spots" here include "dark spots" that are unresponsive and "bright spots" that are always shining. We still have to refer to the results to know how many bad points should appear under normal circumstances.
Don't be too happy when we see "no bright spot", which shows that there may be dark spots in the grade standard, and the meaning of "no dark spot" is the same.
It goes without saying that "no bad point" is the highest realm. If you find one, go to the merchant to change it, whether it is bright or dark.
Also, pay attention to where the bad spots appear. The same number of bad spots appear in different positions, which is also the standard of influencing the level. We always don't want a point in the center of the screen that is never bright or always bright, if we can stand it in the corner.
resolution ratio
Resolution refers to the number of display pixels per unit area. The display of liquid crystal panel is like a small door arranged to let light pass through, and the number of pixels that liquid crystal can display is determined by the number of "small doors" per unit area, which determines that the physical resolution of liquid crystal is fixed, but it is impossible to use the same resolution all the time in our daily life.
For CRT display, as long as the deflection voltage of electron beam is adjusted, different resolutions can be changed. But it is much more complicated to realize on LCD, and the display effect must be simulated by operation, and the actual resolution has not changed. Because not all pixels are enlarged at the same time (for example, the magnification from 800x600 resolution to 1024x768 resolution is 1.28), there is a scaling error. When LCD is used under non-standard resolution, the display effect of text will be worse and the edge of text will be blurred. When buying a liquid crystal, don't just look at the brightness contrast and forget to look at the physical resolution.
visible angle
The viewing angle of LCD is really a headache. When the backlight passes through the polarizer, the liquid crystal and the alignment layer, the output light will be directional. In other words, most of the light is emitted vertically from the screen, so when you look at the LCD from a larger angle, you can't see the original color, or even see all white or all black. In order to solve this problem, manufacturers also began to develop wide-angle technology. So far, there are three popular technologies: TN+ thin film, IPS (in-plane exchange) and MVA (multi-domain vertical arrangement).
The first is TN+ membrane technology, which is to add a wide-angle compensation film on the original basis. This compensation film can increase the viewing angle to about 150 degrees, which is a simple and easy method and widely used in liquid crystal displays. But this technology can't improve the performance such as contrast and response time. Maybe TN+ film is not the best solution for manufacturers, but it is the cheapest solution, so most factories in Taiwan Province use this method to build 15-inch LCD.
IPS(IN-PLANE -SWITCHING) technology claims that it can make the visual angle of up, down, left and right reach 170 degrees. Every coin has its two sides. Although IPS technology increases the viewing angle, using two electrodes to drive liquid crystal molecules requires more power consumption, which will increase the power consumption of liquid crystal displays. In addition, it is fatal that the response time of driving liquid crystal molecules will be very slow.
MVA (multi-domain vertical alignment) technology, the principle is to add protrusions to form multiple visual areas. Liquid crystal molecules are not completely vertically aligned at rest, but horizontally aligned after voltage is applied, so that light can pass through each layer. MVA technology improves the viewing angle to more than 160 degrees, and provides shorter response time than IPS and TN+ films. This technology was developed by Fujitsu. At present, Chi Mei in Taiwan Province Province (Chi Li is a subsidiary of Chi Mei in Chinese mainland) and AUO in Taiwan Province Province are authorized to use this technology.
In addition to the above three wide-angle technologies, there are ASV technology exclusive to Sharp, the father of liquid crystal, PVA, a variant of Samsung in South Korea, and FFS, an IPS variant of HYDIS in South Korea.
The visual range is divided into parallel visual range and vertical visual range. The horizontal visual range is centered on the vertical central axis of the liquid crystal, and the range of the image can be clearly seen by moving left and right. The vertical visual range is centered on the parallel central axis of the display screen, and the range of the image can be clearly seen by moving up and down. The viewing angle is in degrees. At present, the commonly used labeling form is to directly label the total horizontal and vertical range, such as 150/ 120 degrees. At present, the lowest viewing angle is 120/ 100 degrees (horizontal/vertical). Below this value is unacceptable, and it is better to reach 100 degrees.
other
There are other parameters of LCD, such as weight, border width, whether there are speakers, video interface, DVI interface, whether it can be rotated and so on. These personalized designs need users to choose according to their own needs.
I wish you success in finding an LCD that suits you.
It seems that the output is not a big problem, but the quality may not catch up with others in Japan!