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Can DMD display a frame of image within 300 microseconds?

Prince Ma
Prodigy 65 points

Hello, Mr/Ms

I’ve been working on a special projector program using DMD. My research group has already bought the DLP®Discovery 4000 Starter Kit. This project is kind of different from the usual visual projector system. It is required a single frame of image with a grayscale of 8 bits to be displayed within 300 microseconds (probably this constraint could be extended a little bit , but not too much). Well, we only care about the “on” state of the micromirror device because the receiver woks as a integrator of  the luminous intensity. Could this system be synthesized?

  • 0
    TI__Expert 3515 points

    Hello Prince Ma,

    The Grayscale bit depth is primarily driven by the minimum DMD mirror on time.  The Minimum time to load data, Reset, and Reload new data on the DMD mirrors is shown in the below diagram:

    For an XGA device the Load Data block time is ~ 2us.  Therefore total time to load and reload any mirror or group of mirrors is approximately 15 us (2+5+8 as shown above).  THerefore, for the XGA DMD the minimum mirror on time is 15 us, and consequently this is the minimum bit depth.

    Thus, for a 300 us time line, one could achieve the following using a binary grayscale:

    bit 0 - 15us

    bit 1 - 30 us

    bit 2 - 60 us

    bit 3 - 120us

    Total = 120 + 60 + 30 + 15 = 245us.  Therefore, you can achieve about 4.25 gray scale bit depth in every 300 us assuming on PWM (Pulse width modulation) time of the mirrors.

    Potentially, if you have control over the amplitude of the light source during the bit times, then you could potential increase the bit depth.  This could be accomplished by reducing the power of the light to 50% during the Bit 0 time to create a new effective bit of 7.5us.

    Anyway, I think this should give some explanation of the theory.  Let us know if you have any further questions.