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DLP2021LEQ1EVM: Projection Artifact

Will Rodriguez
Prodigy 55 points
Part Number: DLP2021LEQ1EVM

Tool/software:

I'm getting the below projection artifact on one of our DLP2021LEQ1EVM units. Any idea what it could be? 

  • 0
    TI__Expert 8775 points

    Hello Will,

    Thanks for reaching out through E2E!

    I am assigning this to a member of my team to take a look at.

    Best,

    Aaron

  • 0 in reply to Aaron Black
    TI__Expert 5150 points

    Hi Will,

    Sorry for the delay. We've been a bit swamped here and somehow missed this. I can take charge of this as a secondary person for this product.

    May we get some context on what your application is? Are your optics and mechanical assembly put together correctly, as in everything is aligned, and assembly is properly tightened? I would double-check this just in case for now. Just trying to be thorough and not miss the easy stuff first. Thanks!!

    Regards,
    Michael Ly

  • 0 in reply to Michael Ly
    Prodigy 55 points

    All screws are fully fastened. There is a light leak underneath the unit on the edge adjacent to the interposer holder. The bottom plate does not seem to be misaligned so I'm not sure why this leak is occurring. See attached images.

  • 0 in reply to Will Rodriguez
    TI__Expert 5150 points

    Hi Will,

    Let me ask another one of our engineers and maybe an optics person here in our team. Is it just this single unit as you have said, or have additional units also shown this issue? Does swapping parts eliminate this? Does the issue follow the assembly or DMD? This may help us narrow down the issue if it is just a single unit with the issue.

    Regards,
    Michael Ly

  • 0 in reply to Michael Ly
    Prodigy 55 points

    We have another unit that has the same issue.

  • 0 in reply to Will Rodriguez
    TI__Expert 5150 points

    Will,

    Okay, thanks for the update. I'll relay this to our engineers.

    Regards,
    Michael Ly

  • 0 in reply to Michael Ly
    TI__Expert 5150 points

    Hi Will,

    I've just received updates from our optics team as well as another colleague who works on this EVM.

    The DGP EVM uses a field lens design. What you are seeing is a ghost image from the field lens. - Optics Team

    Our other engineer says that this ghost image is expected due to the field lens design above--for DGP designs, this ghost image is only visible in a solid black image case, and it is usually washed out by non-black content such as an OEM logo or animation.
    In a real-world setting, the ghost image artifact is not noticeable on the street/asphalt--as is the case for the DGP projection surface.
    This is a tradeoff: we have a low-cost field lens design with a focal range of 850-1150mm (side mirror height for sedans to SUVs) to avoid having to manually focus each module, but be forced to deal with the ghost image.

    I understand that you are currently in the evaluation phase, but what surface will your final design be projecting onto? What are you currently projecting onto as well? If this is sensitive information, we can take this offline. I'll send a friend request in the case that it is.

    I am marking this thread as "Resolved" because it explains what the phenomena you are seeing is and explains why ghosting occurs. You are more than welcome to comment to open this thread back up by posting another comment, especially because I did ask a couple extra questions.

    Regards,
    Michael Ly