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DLP9000X: Nonlinear power with respect to grayscale, and weird jumping

Zhiguang Liu
Prodigy 60 points
Part Number: DLP9000X
Other Parts Discussed in Thread: , DLP9000, DLPC900

Hi,

We have DMD devices with DLP9000X and DLP9000XUV chips (V-9001 and V-9001UV, ViALUX). When doing the calibration of grayscale, we found that the output power is not proportional/linear to the grayscale. Also, weird jumping was observed at specific grayscale, such as 32, 64, 128...

Can you please help me to figure out the reason? And how to avoid the weird jumping and build a linear relationship between grayscale and the output power. Thanks!

Best,

Zhiguang

  • 0
    TI__Mastermind 48045 points

    Hello Zhiguang,

    This suggests that you are using a continuous illumination source and not a source that is modulated using the LED_ENABLEs.  If the illumination is continuous, then there will be illumination for some of the shorter bits that should have dark time and will therefore skew the values.  You will need to find a way to modulate the illumination with the LED_ENABLEs. 

    FIzix

  • 0 in reply to Fizix
    Prodigy 60 points

    Hi Fizix,

    Thank you for the answer. It makes sense that the DMD doesn't provide a perfect grayscale projection due to dark time and switching time, thus modulation on LED side is necessary. Where can I find the information about "LED_ENABLEs", or should I reach out to ViALUX?

    Zhiguang

  • 0 in reply to Zhiguang Liu
    TI__Mastermind 48045 points

    Hello Zhiguang,

    I should have looked closer.  I read that as the DLP9000 and missed that it was an X, since you were asking about gray-scale measurements.  The principle is the same, but the chip-set does not natively provide these outputs like the DLPC900 chip-sets.  

    However, the DLP9000X can operate significantly faster.  The caveat is that any gray-scale functionality must be provided by the designer.  In this case you will definitely need to reach out to ViALUX and ask them about their implementation for gray-scale on the unit you have from them.

    Fizix