Full-color LED displays are increasingly favored by the market due to their excellent brightness and color performance, as well as seamless picture integrity. However, in some cities, problems such as high brightness of LED display screens have affected the lives of surrounding residents and traffic. How to adjust the brightness and color of the LED display, here are some tips from the editor of Winbond Ying Optoelectronics.
Full color led display
Choice of primary color wavelength
LED display screens are widely used in various industries, and different application places have different requirements for the wavelength of the primary color of the LED. Some of the wavelengths of the primary color of the LED are selected to achieve a good visual effect, and some are to meet people's requirements. Habits, and some are more regulated by industry standards, national standards and even international standards. For example, the choice of the wavelength of the primary color of the green tube in a full-color LED display; in the early days, people generally used a yellow-green LED with a wavelength of 570nm. Although the cost is lower, the color gamut of the display is small, the color reproduction is poor, and the brightness is low. After choosing a pure green tube with a wavelength of 525nm, the color gamut of the display screen has nearly doubled, and the color reproduction has been greatly improved, which greatly improves the visual effect of the display screen. For another example, on the stock market display screen, people are usually accustomed to using red to indicate stock price increases, green to indicate stock prices falling, and to indicate flat prices. In the transportation industry, national standards strictly stipulate that the blue and green bands are traffic, and the red bands are forbidden. Therefore, the choice of the wavelength of the primary color is one of the important aspects of the LED display.
Full color led display
Brightness adjustment
1. Modulate the pulse width, use the frequency of the change that the human eye can feel, and use the pulse width modulation method to achieve grayscale control, that is, periodically change the light pulse width. Pulse width modulation is more suitable for digital control and has been widely used. The most common method is to adopt a microcomputer. At present, almost all LED displays adopt pulse width modulation to control the gray level.
2. Ordinary LED tubes allow a continuous task current of about 20 mA. By changing the current flowing through the LED, except for the saturation of the red LED, the brightness of the remaining LEDs is basically proportional to the current flowing.
Adjustment of white field color coordinates
White field color coordinate adjustment is one of the most basic technologies for full-color LED displays. However, in the mid-1990s, due to the lack of industry standards and basic testing methods, the white field color coordinates were usually determined by human eyes and sensations, resulting in serious color cast and randomness of white field color temperature. With the promulgation of industry standards and the completion of testing methods, many manufacturers have begun to standardize the color matching process for full-color screens. However, due to the lack of theoretical guidance for color matching, some manufacturers often sacrifice the gray levels of certain primary colors to adjust the 100-field color coordinates, and the overall performance cannot be improved.
Color adjustment
The high-definition LED display is displayed according to the principle of the three primary colors of light. Determining one of the red, green, and blue colors as the reference is mainly based on the different brightness of the red, green, and blue colors of the selected product. Generally, the brightness reference is the one with low brightness ratio. When the maximum brightness has been reached, for a two-color LED display, another color needs to be adjusted, and for a full-color LED display, the colors of the other two LEDs must be adjusted.
