As the technology of LED display screens continues to mature, the requirements for LED large screens are getting higher and higher, from monochrome to full color. The following two methods of controlling two LED large screens are introduced: One is to change the current flowing through the LED. The ordinary LED tube allows the continuous task current to be around 20 mA. Except for the saturation of the red LED, the brightness of the other LEDs is basically proportional to the current flowing; however, this adjustment method is Simple, but with the gradual improvement of LED large screen requirements, it is increasingly unsuitable for fast and accurate modulation. The following accepts a commonly used modulation method; Another method is pulse width modulation (PWM), which uses a pulse width modulation method to achieve gray scale control using a frequency that can be perceived by the human eye, that is, periodically changes the optical pulse width (ie, duty cycle). Only this cycle of repeated lighting is short enough (ie, the refresh frequency is high enough), and the human eye does not feel that the illuminating pixels are shaking. Since pulse width modulation is more suitable for digital control, it has been widely used. A common method is to adopt a microcomputer to provide an LED display. Almost all LED screens currently use pulse width modulation to control gray levels. The LED control system is generally composed of three main parts: the main control box, the scanning board and the display and control installation. The main control box obtains the color brightness data of one screen pixel from the computer display card, and then newly allocates to several scanning boards, each of which serves as a plurality of rows (columns) on the control LED screen, and each row (column) The LED display signal is transmitted serially. At present, there are two ways of serially transmitting display control signals: one is to control the gray level of each pixel on the scanning board, and the brightness values ​​of the pixels of each row of the scanning board not from the control box are stopped to be synthesized (ie, pulse width modulation). Then, the old-fashioned signals of the LEDs of each row are transmitted in a serial manner to the corresponding LEDs in a pulse manner (lighting is 1 and not litting to 0) to control whether the LEDs can be lit. This method uses fewer devices, but the amount of data transmitted serially is larger, because each pixel requires 16 pulses at 16 gray levels in a period of repeated lighting, and is required at 256 gray levels. 256 pulses, due to the frequency of the device task, the LED screen can only achieve 16 gray levels. Another method is that the serial transmission of the scanning board is not a switching signal of each LED but an 8-bit binary luminance value. Each LED has its own pulse width modulator to control the lighting time. Thus, in a cycle of repeated lighting, each pixel point requests only 4 pulses in 16-level gray scale, and only 8 pulses in 256-level gray scale, which greatly increases the serial transmission frequency. This method of controlling the gray level of the LED can easily realize 256-level gray scale control locally. Parabolic Reflex Reflector,Parabolic Grow Reflector,Aluminum Lamp Reflector,Safety Lighting Covers Yangzhou Huadong Can Illuminations Mould Manufactory Co., Ltd. , https://www.light-reflectors.com
LED panel: LED is the light emitting diode, the abbreviation of LED, referred to as LED. It is a display mode by controlling a semiconductor light-emitting diode, which is roughly composed of a plurality of light-emitting diodes that are usually red, and displays characters by turning on and off the light. A display screen for displaying various information such as text, graphics, images, animations, quotes, videos, and video signals.