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Static Pattern?

Raymond Santoso
Prodigy 120 points
Other Parts Discussed in Thread: DLPC300

Hi everyone,

I am using the DLP Lightcrafter (with DLP3000 chip) to reflect a low power laser beam. However, when I tried to set all the pixels to the ON/OFF state (with Internal Test Pattern -> Solid Black or Solid White), I observe a fluctuation in the beam intensity that I don't observe by replacing the DLP with a mirror.

My question is, can I be sure that for the Internal Test Pattern and Static Image sections of the Lightcrafter, the patterns displayed are really static (no refresh)?

Thanks in advance for your helps!

Raymond

  • 0
    TI__Mastermind 30875 points

    Hello Raymond,

    In the TestPattern and Static image mode the pixels are refreshed, this configuration is mimicking a basic video sequence that is used in a regular data projector system. 

    Looking at your application, please try 1bit internal pattern sequence mode, you will be able to get the better result.

    Regards,

    Sanjeev

  • 0 in reply to Sanjeev
    Prodigy 120 points

    Dear Sanjeev,

    Thank you again for the fast reply. I tried the pattern sequence mode as you suggested, but somehow I always have the error message "Command FAILED" when I tried to press Set in the Pattern Setting tab.

    I wonder if this is happening because I had removed the connection cables to the LED. If this is so, is there any way to fix this?

    Regards,

    Raymond

  • 0 in reply to Raymond Santoso
    Intellectual 425 points

    Hello Raymond,

    make sure you set first the "pattern sequence mode" in the display mode panel.  If you had removed the all light engine form the board and if you had installed the latest version of the firmware (3.0 software bundle) there shouldn't be any problem even without light engine.

    Check also the version of your lightcrafter, if is 2.0 or 1.0.

    Pablo

  • 0 in reply to Sanjeev
    Prodigy 120 points

    Hi Sanjeev,

    May I ask you how does the pattern displayed in the Static Image and Test Pattern mode?

    For example, if I choose the Solid Black pattern in the Test Pattern section, does each mirror pixel refreshes back and forth between the 'Black' state and the 0 degree state? If yes, do you know at what rate is this happening?

    Thanks and regards,

    Raymond

  • 0 in reply to Raymond Santoso
    TI__Mastermind 30875 points

    Hi Raymond,

    The general principle explained here http://www.ti.com/lit/ug/dlpu006c/dlpu006c.pdf section 4.1.

    In the test pattern or static image mode DLPC300 enables degamma and other image enhancement (like dithering) algorithms to increase the perceived contrast of the image. In simple words the o/p light in this mode is non-linear to of actual data input.

    About the 2nd question, when you display a black image in static image or test pattern mode, basically you are running the above mentioned video sequence, since all 24bits data is '0' across the entire display time in a black frame you won't see much of activity at the light o/p, referring back to user guide section 4.1, between each bitplane display each mirror goes through two operation state, LOAD and RESET, RESET state is when actual light modulated by the mirror based on the data loaded, in the example every where it is '0' so mirror reset from black to black state, if you put a photodector you will notice a small damping signal < 5us at the beginning of each RESET state.

    The FLAT state or 0-degree state is invalid state during DMD operation, only during DMD PARK(no operation) mode.

    Suggestion, if you are looking for modulating light as a linear function of input pixel data, it has to be pattern sequence mode. 

    Regards,

    Sanjeev