With the LED display applications more and more widely, LED display is the outdoor advertising applications much attention, people slowly on the LED display inherent characteristics of awareness has deepened. The recent passers-by and drivers have to reflect the problem of high brightness, mainly reflected in the pedestrian eyes feel uncomfortable, shaking the driver's eyes, affecting sleep and so on. In order to let the city away from the LED display too high brightness problems,
First, adjust the brightness
1, to change the current flowing through the LED, ordinary LED tube to allow continuous task current in 20 mA or so, in addition to red LED saturation phenomenon, the rest of the LED brightness is basically proportional to the flow of current.
2, pulse width modulation (PWM), the use of the human eye can feel the frequency of change, with the pulse width modulation method to achieve gray-scale control, that is, periodically change the pulse width (that is, duty cycle), only this Repeatedly light up the cycle is short enough (ie, the refresh frequency is high enough), the human eye is unable to feel the luminous pixels in trembling. As the pulse width modulation is more suitable for digital control, so get a lot of use. The common way is to use the computer to provide LED display. Almost all of the current LED screen is the use of pulse width modulation to control the gray level.
Second, the color adjustment
LED display products are based on red, green, blue color LED lights to adjust the brightness of the entire screen. We choose the product according to the red, green and blue color brightness ratio to determine which color as a benchmark, generally a low brightness ratio as a light reference, when the benchmark has reached a maximum brightness, adjust the other (Two-color) or two (full color). When the display screen is two colors, most of the case to green as the base, adjust the red diode operating current. Generally to reduce the operating current to balance the color yellow for the adjustment criteria, so it is necessary to reduce the brightness of the entire display screen. When the color of the display is adjusted to the best balance, the brightness of the screen is reduced. If the display screen in order to achieve the brightness requirements, each color will reach the maximum brightness, then lost the color balance, for example: two-color screen yellow color reddish, or green.