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How to calculate the current and the light can stay white?

Chuang Chiao-Wei
Prodigy 100 points

Dear all,

In pattern sequence, I can display the patterns with red, green, blue, and the LED current  values :  R:104, G:135, B:130.

Now I face the problem that the illuminance of the DLP is too high.

As far as I know, there is a method to reduce the illuminance by adjust the current.

How to calculate the Red, Green and Blue LED current and the light can stay white?

Thanks ,

Athena

  • 0
    TI__Mastermind 30875 points
    Hello Athena,

    Unlike regular LED projectors there is no auto-white adjustment feature in these controller chips. The purpose of the controller chips is to accurately reproduce the grayscale intensities.

    You can follow a crude method -

    Keep R:G:B color ratio constant; this further comes with an assumption that the LED current to actual intensity and wavelength is constant.

    For example: For 104:135:130,

    R% = 104/(104+135+130) = 28.18%
    G% = 135/(104+135+130) = 36.58%
    B% = 130/(104+135+130) = 35.23%

    So R:G:B are 28.18%:36.58%:35.23% = 99.99% (~ 100%),

    so if you chose any low current from this equation, you can keep the current ratio constant, like, if you chose G current to 100, now R and B must be adjusted in such a way that the R:G:B ratio is kept constant.

    Regards,
    Sanjeev