LED has now penetrated into all walks of life. On the road, we can see the warm reminder signs on the LED display of the road. At the door of the store, we can see the advertising signs of the LED display used by the store. It can be said that the LED display has reached the limitless Therefore, it is essential for us to master some common sense of LED display. Let's follow our LED display manufacturer---Shenzhen YONGS Co., Ltd. to understand the control method of LED display brightness.
Il existe deux manières de contrôler la luminosité des LED. L'une consiste à modifier le courant traversant la LED. Généralement, le courant de travail continu du tube LED est d'environ 20 mA. Hormis le phénomène de saturation de la LED rouge, la luminosité des autres LED est essentiellement proportionnelle au courant qui la traverse ; l'autre méthode consiste à utiliser l'inertie visuelle de l'œil humain, en utilisant la méthode de modulation de largeur d'impulsion pour obtenir un contrôle des niveaux de gris, c'est-à-dire pour modifier périodiquement la largeur d'impulsion lumineuse (c'est-à-dire le rapport cyclique), tant que la période d'éclairage répété est suffisamment court (c'est-à-dire que la fréquence de rafraîchissement est suffisamment élevée), l'œil humain ne peut pas percevoir le tremblement des pixels émetteurs de lumière-. Étant donné que la modulation de largeur d'impulsion est plus adaptée au contrôle numérique, presque tous les écrans LED utilisent aujourd'hui la modulation de largeur d'impulsion pour contrôler les niveaux de gris, alors que les micro-ordinateurs sont généralement utilisés pour fournir un contenu d'affichage LED.
The LED control system usually consists of three parts: the main control box, the scanning board and the display 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 each row (column) The display control signal of the upper LED is transmitted in a serial manner. At present, there are two ways to serially transmit display control signals: one is to centrally control the grayscale of each pixel on the scanning board, and the scanning board decomposes the brightness value of each row of pixels from the control box (ie, pulse width modulation), Then, the turn{{0}}on signals of the LEDs in each row are transmitted to the corresponding LEDs in a serial manner by row in the form of pulses (1 when they are on, 0 when they are not on) to control whether they are lit. This method uses fewer devices, but the amount of data transmitted serially is larger, because in a cycle of repeated lighting, each pixel needs 16 pulses under 16-level grayscale and 256-level grayscale. 256 pulses, due to the limitation of the operating frequency of the device, generally only the LED screen can achieve 16-level grayscale.
Another method is that what the scanner board serially transmits is not the switching signal of each LED but an 8-bit binary brightness value. Each LED has its own PWM to control the lighting time. In this way, in a cycle of repeated lighting, each pixel only needs 4 pulses under 16-level grayscale, and only 8 pulses under 256-level grayscale, which greatly reduces the serial transmission frequency. With this method of decentralized control of LED grayscale, 256-level grayscale control can be easily realized.
The above is the control method of the brightness of the LED display screen. When we master it, we can control the brightness of the LED display screen well, so that it can maintain the brightness we need at any time.
