Parameters Related To LCD Screen

- Dec 04, 2018-

1. Resolution 

Resolution is a very important performance indicator. It refers to the number of points that can be displayed horizontally and vertically on the screen (the lines and polygons displayed on the screen are made up of points), and the higher the resolution, the more information can be accommodated in the same screen. For a CRT that supports 1280x1024 resolution, both 320x240 and 1280x1024 resolution can be more perfectly represented (because the electron beam can be flexibly adjusted).

However, its maximum resolution is not necessarily the most appropriate resolution, because if the 17-inch display on the 1280x1024 resolution, Windows fonts will be very small, a long time eyes will be prone to fatigue, so the best resolution of the 17-inch display should be 1024x768. But not for the LCD. The maximum resolution of an LCD is its true resolution, which is the best resolution. Once the resolution set is less than the real resolution (for example, the 15-inch LCD, with a true resolution of 1024x768, and Windows has a resolution of 800x600), there will be two ways to display it. First, the center shows that only the 800x600 dots in the middle of the LCD will display the image, other unused points will not glow, maintain a dark background, it appears that the picture is centered. The other is an extended display that uses every pixel on the screen, but because pixels are prone to distortion, it can have some impact on the display.

So anyway, when choosing LCD, pay attention to the resolution is not the bigger the better, but the appropriate use.

2. Perspectives

Most flat-level displays can reach 180 degrees, meaning that what is displayed is clearly visible from any direction in front of the screen. The LCD is different, and its visual angle varies according to whether the process is advanced or not. On the market, the visual angle of the first-line brands, such as Asus, Samsung, LG and other products can reach the level of 170 degrees, while some of the displays with a wide viewing angle can reach 178 degrees, which is very close to the 180 degrees of the CRT. Once the user is in use, once the angle of view is beyond its actual visual range, the color of the screen will decrease, darken, and even appear like a negative image situation.

It's possible that everyone is confused by Philips ' ads. In fact, the LCD perspective is not very large, but much smaller than CRT, is a significantly weaker than CRT place.

3. Visible Area

Visual area refers to the area of the part of the screen that can be used to display an image in a practical application. Because the size of the CRT display is actually the size of its picture tube, the part that can be used to display the image simply does not reach this size, because the frame of the picture tube takes up a portion of the space. Generally speaking, the visual area of the 17-inch CRT display is about 15.8-16 inches, while the visible area of the 15-inch display is only about 13.8 inches. But for LCD, the nominal size is basically the size of the visible area, the space occupied by the border is very small, 15 inch LCD visual area is about 14.5 inches, which is why the LCD looks larger than the same size CRT.

So when you buy LCD 15 inches is basically enough.

4. Brightness and contrast

LCD display function is mainly a backlight light source, the brightness of this light source determines the screen brightness of the entire LCD and color saturation. Theoretically, the higher the brightness of the LCD, the better, the brightness of the measurement unit for cd/m2 (square candlelight per meter), also known as the NIT lumens TFT screen brightness is mostly from 150Nits start, usually 200Nits can show a better picture. Contrast is the contrast measurement between black and white colors at different levels. Contrast 120:1 can show vivid, rich colors (because the human eye can tell the contrast of about 100:1), the contrast rate reached 300:1 can support the color of each order, most LCD display contrast is around 500:1~800:1. And such as Asus, Samsung, LG and other first-line brands of liquid crystal display product contrast is generally about 1000:1, there is not a set of fair standard values to measure the contrast between brightness and contrast, so the purchase of LCD all rely on a pair of sharp eyes.

So in the purchase of LCD should pay attention to this indicator, it is also LCD products on the biggest difference in performance of a link estimated to buy some difficulty.

5. Reaction speed

The time unit for measuring the reaction speed is milliseconds (ms), which refers to the time it takes for the pixel to be dimmed from bright and lit by dark turn. The smaller the value, the smaller the value, indicating the faster the reaction speed. Mainstream LCD response speed is more than 25ms, in the general commercial use (such as word processing or text processing) does not have much to do, because such uses do not have to care too much about the LCD response time. And if it is used to play games, watch Vcd/dvd and other full-screen high-speed dynamic images, reaction time is particularly important, if the reaction time is longer, the screen will appear trailing, residual shadow and other phenomena. For a simple example, the vast majority of LCD displays on the market will have different degrees of trailing when playing QUAKE3, especially when the screen is updated at high speed.

CRT, on the other hand, does not have this problem at all, because the CRT's reaction time is only 1ms, there is absolutely no trailing phenomenon.

6. Color

When it comes to color, LCD is not as good as CRT, in theory, CRT can display the same color as the TV set is infinite. and the LCD can only display about 260,000 colors, most of the products are declared to be able to display 16.77 million colors (16777216 colors, 32 bits), but in fact it is achieved through the jitter algorithm (dithering), compared with the real 32-bit color is still a big gap, Therefore, in the color performance and transition is still less than the traditional CRT. By the same token, LCDs are less capable of performing grayscale than CRT. If you have the conditions, you can compare it yourself: Find a 17-inch terry Picture tube monitor, and then put on a 15-inch LCD, while displaying a 16.77 million-color image. CRT shows the picture is very bright, and LCD appears to have some  "fake ", although can not say where the wrong, but look is not that the CRT comfortable.