Is there any relationship between brightness and gray level of LED display?

Many friends do not understand the relationship between the gray level and brightness of led. Some people think that the two are not related or juxtaposed. Some people think that the two are just different names, but they are actually a type.

LED gray level can also be called LED brightness. Gray level, also known as Half-tone, is mainly used to transmit pictures. There are 16, 32 and 64 levels respectively. It uses matrix processing to process the pixels of files into 16, 32 and 64 levels to make the transmitted pictures clearer. Whether it is monochrome, bichrome or trichrome screen, to display images or animation, it is necessary to adjust the gray level of each LED light-emitting pixel. The degree of fine adjustment is what we usually call gray level.

Is there a relationship between the gray level and brightness of LED display

There are two methods to control the gray level of LED: one is to change the current flowing through, the other is pulse width modulation. 1. Change the current flowing through the LED. Generally, the continuous working current of the LED tube is about 20 mA. Except for the saturation of the red LED, the gray level of other LEDs is basically proportional to the current flowing through. Another method is to use the visual inertia of the human eye and use pulse width modulation to achieve gray level control, that is, to periodically change the pulse width (i.e. duty cycle), as long as the period of repeated lighting is short enough (i.e., refresh frequency). The rate is high enough) the human eye can't feel the fluorescent pixels shaking. Because pulse width modulation is more suitable for digital control, almost all LED screens use pulse width modulation to control the gray level today, which is widely used to provide LED display content. The control system of LED is usually composed of three parts: the main control box, the scanning board and the display and control device.

The main control box obtains the brightness data of each color of a screen pixel from the display card of the computer, and then redistributes it to several scanning boards. Each scanning board is responsible for controlling several rows (columns) on the LED screen, and the display signal of the LED on each row (columns) is transmitted in a serial way.

At present, there are two ways of serial transmission of display control signals:

(1) The gray level of each pixel is centrally controlled on the scanner board, which decomposes the gray value of each pixel from the control box (i.e. pulse width modulation), and then transmits the open signal of each LED to the corresponding LED in the form of pulse (1, 0) in a row-by-line serial manner to control whether it is lit. This method uses fewer devices, but the amount of data transmitted in serial is large, because in a repetitive lighting cycle, each pixel needs 16 pulses in 16-level gray level and 256 pulses in 256-level gray level. Due to the limitation of device operating frequency, the LED screen can only achieve 16-level gray level.

(2) One is pulse width modulation. The serial transmission of the scanner board is not the switching signal of each LED, but an 8-bit binary gray value. Each LED has its own pulse width modulator to control the lighting time. In this way, in a period of repeated lighting, only 4 pulses are needed for each pixel point in 16-level gray level and 8 pulses are needed in 256-level gray level, which greatly reduces the serial transmission frequency. The 256-level gray-level control can be easily realized by using this method of decentralized control of LED gray-level.

Warm Tip: Choosing and purchasing LED display should not only focus on product quality, but also on the choice of post-service, because we will have various problems in use need of consultation, then the post-service of LED display must be very demanding.