Interpretation of key parameters of LCD screen

Now many electronic products have human-computer interaction interfaces and display screens to enhance the sense of body, such as car charging piles, tablet computers, televisions, and mobile phones that everyone can't live without.

For general LCD screens with low requirements, we may not pay so much attention to them. If they can display normally, it is OK. However, for tablets and mobile phones, body feel is very important, so many indicators of the screen need special attention. What are the key parameters in the specification? Let's get to know!

1. TFT-LCD

In the first item of the specification, TFT-LCD is usually written on the screen we usually use.

TFT (Thin Film Transistor) is a thin film field-effect transistor. The so-called thin-film transistor means that each liquid crystal pixel on the liquid crystal display is driven by the thin-film transistor integrated behind it. Thus, screen information can be displayed at high speed, high brightness and high contrast.

TFT belongs to active matrix LCD, and TFT-LCD is "true color" (TFT).

2. Brightness

Brightness refers to the brightness of the picture. The LCD has a backlight, which is formed by lighting up series and parallel LED. The brightness of LED is generally expressed in Luminous Intensity, and the unit is candela cd, 1000ucd (micro candela)=1 mcd (millicandela).

The higher the brightness is, the better it is. The higher the brightness is, the more uncomfortable it is. On the one hand, it is easy to cause visual fatigue. On the other hand, it also reduces the contrast between pure white and pure black and affects the performance of the color scale and grayscale. Therefore, it is necessary to improve the contrast as well as the brightness, otherwise, the whole display screen will appear white.

The typical brightness value of the products we contact is generally 300-500cd/m2, which is generally described in the manufacturer's specifications.

3. Pixel

The image we see is composed of many small dots, which we call pixels, also called pixels.

In the same physical area, the more pixels, the clearer the image will be displayed, and the fewer pixels, the more blurred the image will be displayed.For example, if there are 20 million pixels in a portrait photo, the pores may be clearly seen. If there are only 1 million pixels, the nose and eyes may be blurred. This is how many pixels are used to describe the clarity of the image.

The more pixels per unit of physical area, the higher the definition.

4. Pixels H x V

The resolution is generally described as M x N, where M represents the number of horizontal pixels and N represents the number of vertical pixels. The total number of pixels in the image is the product of the two.

For example, a 1920X1080 resolution picture represents 1920 pixels horizontally and 1080 pixels vertically. The total number of pixels in this picture is 1920 x 1080=2073600. The resolution is still describing the total number of pixels in a picture. It is just a new description method.

5. Color depth

The color depth does not mean how many colors are covered, but how many gray scales the same color has (it can be simply understood as different brightness of a color). In the world of color depth, "each color is not just one color". Because each color has many gray scales, and the unit is bit.

For example, in an 8-bit display screen, if it is a single channel, then each color light channel is represented by 8 bits. That is, the multiplication of three 2s to the 8th power is equal to the 24th power of 2, which is often called "true color depth". Its total color number has reached 16.7M colors. At present, most mainstream displays adopt this standard.

6. Definition

When we watch movies or TV plays, we can choose standard definition 480P, high-definition 720P, ultra definition 1080P, or even special 4K (4096P).

In 480P, 480 means that the number of vertical pixels in each frame of the video should be at least 480, and P means progressive scanning. Because the display is to scan the pixels on the screen line by line and refreshes dynamically.

When the number of horizontal pixels reaches about 4000, it can be called a 4K screen, not necessarily a specific number. For example, 4096 x 2160 and 3840 x 2160 can be called 4K screens.

7. Frame rate

The frame is a single image with the smallest unit in the image animation. A frame is a static picture. Continuous frames form animation, which creates the illusion of motion, such as in television images.

The so-called frame rate refers to the number of consecutive pictures taken by the camera within one second. Its unit is fps, that is, frame per second. As we all know, the human visual system has a short-term memory ability for images. When different actions of the same image appear continuously, as long as the image's action switching speed is fast enough, the viewer will overlap the previous image when looking at the next image, thus creating an "illusion of movement" of the image.

The visual persistence of human eyes is 24 frames per second, so theoretically, it can be considered smooth if it is greater than 24 frames. However, due to the high change rate of the game screen, the higher the better. If vertical synchronization is enabled, the number of frames should generally be about 60.

Guangzhou Innolux Optronics Co., Ltd

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