Technical parameters of LCD monitors

Technical parameters of LCD monitors

1. Viewable area
The size indicated on the LCD monitor is consistent with the actual screen range that can be used. For example, a 15.1-inch LCD monitor is approximately equal to the visible range of a 17-inch CRT screen.

2. Viewing angle
The viewing angle of the LCD monitor is symmetrical left and right, but not necessarily symmetrical up and down. For example, when the incident light from the backlight passes through the polarizer, liquid crystal and orientation film, the output light has a specific directional characteristic, that is, most of the light emitted from the screen has a vertical direction. If we watch a full white screen from a very oblique angle, we may see black or color distortion. Generally speaking, the up and down angles should be less than or equal to the left and right angles. If the viewing angle is 80 degrees left and right, it means that the screen image can be clearly seen at a position of 80 degrees from the screen normal. However, due to the different ranges of human vision, if you are not standing in the best viewing angle, the color and brightness you see will be wrong. Now some manufacturers have developed various wide viewing angle technologies to try to improve the viewing angle characteristics of LCD monitors, such as: IPS (In Plane Switching), MVA (Multidomain Vertical Alignment), TN + FILM. These technologies can increase the viewing angle of LCD monitors to 160 degrees, or even more.

3. Dot Pitch
We often ask what the dot pitch of LCD monitors is, but most people don't know how this value is obtained. Now let's find out how it is obtained. For example, the viewing area of ​​a general 14-inch LCD is 285.7mm × 214.3mm, and its maximum resolution is 1024 × 768, then the dot pitch is equal to: visible width / horizontal pixel (or visible height / vertical pixel), that is, 285.7mm / 1024 = 0.279mm (or 214.3mm / 768 = 0.279mm).

4. Color
LCD is of course the most important color performance. We know that any color in nature is composed of three basic colors: red, green, and blue. The LCD panel is composed of 1024×768 pixels, and the color of each independent pixel is controlled by the three basic colors of red, green, and blue (R, G, B). Most manufacturers produce LCD monitors with 6 bits for each basic color (R, G, B), that is, 64 degrees of expression, so each independent pixel has 64×64×64=262144 colors. Many manufacturers also use the so-called FRC (Frame Rate Control) technology to simulate the full-color picture, that is, each basic color (R, G, B) can reach 8 bits, that is, 256 degrees of expression, so each independent pixel has up to 256×256×256=16777216 colors.

5. Contrast value
The contrast value is defined as the ratio of the maximum brightness value (full white) divided by the minimum brightness value (full black). The contrast value of CRT monitors is usually as high as 500:1, so it is easy to present a truly black picture on a CRT monitor. But it is not easy for LCD. The backlight source composed of cold cathode ray tube is difficult to switch quickly, so the backlight source is always in the state of lighting. In order to get a completely black screen, the liquid crystal module must completely block the light from the backlight source, but in terms of physical properties, these components cannot fully meet this requirement, and there will always be some light leakage. Generally speaking, the contrast value acceptable to the human eye is about 250:1.

6. Brightness value
The maximum brightness of the liquid crystal display is usually determined by the cold cathode ray tube (backlight source), and the brightness value is generally between 200 and 250 cd/m2. The brightness of the liquid crystal display is slightly lower, and the screen will feel dark. Although higher brightness can be achieved technically, this does not mean that the higher the brightness value, the better, because a display with too high brightness may cause eye damage to the viewer.

7. Response time
The response time refers to the speed at which each pixel of the liquid crystal display responds to the input signal. Of course, the smaller the value, the better. If the response time is too long, it is possible that the liquid crystal display will have a sense of tail drag when displaying dynamic images. The response time of a general LCD display is between 20 and 30 ms.