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LEDs are defined in the PN junction of some semiconductor materials. When the minority carriers injected are combined with the majority carriers, the excess energy is released as light, which converts the electrical energy directly into light energy. The PN junction adds a reverse voltage, and minority carriers are difficult to inject, so they do not emit light. The diode produced by the principle of injection electroluminescence is called a light-emitting diode, referred to as LED.
The color and luminous efficiency of LEDs are related to the materials and processes for making LEDs. Currently, red, green and blue are widely used. Due to the low operating voltage of the LED (only 1.5-3V), it can actively emit light and have a certain brightness. The brightness can be adjusted by voltage (or current), and it is resistant to shock, vibration and long life (100,000 hours), so it is large. Among the display devices, there is currently no other display mode that rivals the LED display mode.
A display made of red and green LEDs together as a pixel is called a two-color screen or a color screen; a display screen that puts three LED tubes of red, green, and blue together as a pixel is called a three-color screen or a full screen. Color screen.
Regardless of whether a single-color, two-color or three-color screen is made with LEDs, the brightness of each LED that is required to form a pixel to be displayed must be adjusted, and the degree of fineness of the adjustment is the gray level of the display. The higher the gray level, the finer the displayed image and the richer the color, and the more complex the corresponding display control system. Generally, the image of 256-level gray scale has a very soft color transition, while the color image of 16-level gray scale has a clear color transition boundary. Therefore, color LED screens are currently required to be 256-level grayscale.
LED display working principle LED electronic display is a high-tech product integrating optoelectronics and computer technology.
Performance characteristics of LED products The text LED display and graphic LED display should have the move-in and remove modes and display modes specified in the detailed specifications.
The computer video LED display should have: an animation function. It is required that the LED display animation display is consistent with the area corresponding to the computer display; the text display function. Requires text to display stable, clear crosstalk; grayscale function. It is required to have the grade gray scale specified in the detailed specification. In addition to animation, text display, and grayscale functions, TV video LED displays should be able to display TV and video images. The market LED display has the corresponding market display capability.
How to classify LED displays LED displays can be classified according to the following conditions:
. The environment LED display is divided into an indoor LED display and an outdoor LED display according to the use environment.
. Display color LED display is divided into single primary color LED display (including pseudo color LED display), dual primary color LED display and full color (three primary color) LED display. According to the gray level, it can be divided into 16, 32, 64, 128, 256 gray LED display.
. Display performance LED display is divided into text LED display, graphic LED display, computer video LED display, TV video LED display and market LED display according to display performance. The market LED display generally includes LED displays for securities, interest rates, futures, and the like.
. In the basic light-emitting point non-line type LED display, the indoor LED display can be divided into 3mm, 375mm, 5mm, 8mm, and 10mm display according to the single-point diameter of the LED; the outdoor LED display can be used according to the pixel diameter. It is divided into LED displays such as 19mm, 22mm and mm26. In the market type LED display, the size of the digital tube can be divided into 2.0cm (0.8inch), 2.5cm (1.0inch), 3.0cm (1.2inch), 4.6cmm (1.8inch), 5.8cm (2.3inch), 7.6. LED display such as cm (3 inch).
How to evaluate the quality of LED screen?
. The out-of-control point of the indoor LED display in the out-of-control point is not more than three-thousandths of a percent, and the out-of-control point of the outdoor LED display should be no more than three-thousandths, and it is discrete and strong;
. The consistency of the consistent LED screen is better, the brightness of the whole screen should be balanced, and there is no obvious color block;
. Safety has no safety hazards, leakage current, ground leakage current should not exceed 3.5mA (AC RMS); anti-point strength, LED display can be 50Hz, 1500V (AC RMS) test voltage Lmin should not cause insulation breakdown; At the same time, the LED display should have a warning sign at the fuse and switching power supply;
. Appearance, no obvious scratches on the LED display frame. The outdoor LED display pixel tube should be installed consistently, without looseness and cracked casing;
. The structure and the LED display part can be made of steel, aluminum, wood, etc., and the structure is required to be firm and beautiful.