How to reasonably control the brightness of LED display
Release time:
2024-05-20
We know that if the brightness of an LED display is too high, it will cause damage to people's eyes. Generally, the brightness suitable for people's visual effects is between 120cd/m2 and 150cd/m2. However, as the technology of LED display continues to mature, the requirements of LED large screen are getting higher and higher, from monochrome to full color.
Here are two control methods for two LED large screens:
One is to change the current flowing through the LED. Ordinary LED tubes allow the continuous task current to be around 20 mA. Except for the saturation of red LEDs, the brightness of other LEDs is basically proportional to the current flowing through them. However, although this adjustment method is simple, with the gradual improvement of LED large screen requirements, it is becoming more and more unsuitable for fast and accurate modulation. The following is a commonly used modulation method;
Another method is pulse width modulation (PWM), which uses the frequency of changes that the human eye can feel, and uses pulse width modulation method to realize gray scale control, that is, periodically changing the light pulse width (I. e. duty cycle). As long as the repeated lighting period is short enough (I. e. the refresh frequency is high enough), the human eye cannot feel the light-emitting pixels shaking. Since pulse width modulation is more suitable for digital control, it has been widely used. The common method is to adopt a microcomputer to provide LED display mode. At present, almost all LED screens adopt pulse width modulation to control the gray level.
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