LED display brightness adjustment
There are two ways to adjust the brightness of the full-color LED display: automatic adjustment and manual adjustment. Among them, automatic adjustment is an intelligent adjustment method of brightness adaptively based on ambient brightness, and manual adjustment method is realized through software, so let’s see if it is useful to use software to adjust the brightness of the display screen?
The current software to adjust the brightness is generally 256-level adjustable. In fact, the software is just an operation interface. What is finally changed through the operation of the software is the PWM duty cycle of the LED display driver to realize the change of brightness.
There are two ways to control the brightness of the LED display:
One is to change the current flowing through the LED display screen. Generally, the current allowed by the LED tube to work continuously is about 20ma. Except for the saturation phenomenon of the red LED, the brightness of other LEDs is basically proportional to the current flowing; the other method is Using the visual inertia of the human eye, the pulse width modulation method is used to achieve grayscale control, that is, the light pulse width (ie duty cycle) is periodically changed. As long as the refresh frequency is high enough, the human eye cannot feel the light-emitting pixels are shaking. . Because pulse width modulation is more suitable for digital control, almost all LED display screens use pulse width modulation to control gray levels today when microcomputers are generally used to provide LED display content.
At present, the brightness of the outdoor full-color LED display must be above 1500cd/m2 to ensure the normal operation of the display, otherwise the displayed image will not be clearly seen because the brightness is too low. However, at present, the brightness of many outdoor LED displays exceeds 5000cd/m2, and the playback effect is good during the day. However, such high brightness at night will cause serious light pollution and cause trouble to nearby residents.
Therefore, it is very necessary to determine the brightness of the LED display screen. Adjusting the brightness through software is a necessary method and a common practice in the industry, which is an effective method.