The LED tricolor PWM dimming

The LED tricolor PWM dimming

PWM Dimming (pulse width modulation, pulse width modulation) is a relatively common, and application of regulation in the best LED gray. PWM said the easy to understand, is to control the proportion of time LED opening and closing, opening and closing of the proportion of the time will be divided into several levels, LED will display the corresponding number of gray scale.


As for the PWM frequency, just said PWM is the time to open and close the LED to achieve, but the number of switches can not be too low, at least to deceive the eyes. Drawing on the experience of the TV is generally greater than 100Hz, some LED display screen will be subject to the camera shooting, under the conditions of the proposed design in the 300-500Hz more reasonable.


In the primary design applications is usually, by adjusting the LED current to achieve the maximum brightness of the white balance and expectations, by controlling the PWM to achieve gray level. There are 7 order, 8 order, 16 order, 32 order, 64 order, order, 128 order, 256 order, 512 order, order, order, order, order, and so on. It can also be a different order of orders, which is mainly for digital line data processing. For example, to be divided into 100 order, it is also possible.


Gray level product of RGB, is the number of products can be reproduced in color theory, we usually say how many colors. For example: monochrome is 256 color, red 256 (grade) x 256 (level) * Blue 256 (class) = 16777216 (16KK color).


Monochrome 256 gray has fully meet the needs of the eye color gamut, LCD liquid crystal display at present is this, is currently one of the largest gray scale IC support. Because of the large LED color difference is the use of 512 order gray, the actual use of the partial gray scale correction. 512 gray scale is more representative of the IC, MBI5030, TLC5940, DM137, DM133, DM412 etc.. Design method of point correction. This method is used to calibrate each pixel in a large display. After calibration is completed, or when the display is adjusted to a certain brightness, each pixel can provide the same level of brightness.


Other low gray levels, can according to the needs of different options in the design. For example, in the commercial decorative lighting above 32 steps is enough, the text symbols and other will be lower. Monochromatic illumination brightness adjustment 16 order to meet the requirements.