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DLP670S: DLP670S

Bin Wang
Prodigy 40 points
Part Number: DLP670S

Tool/software:

Hi,

I am working on the 3D printer design based on the DMD chips. I now have two DMD chips, the DLP 6500 and DLP 670s. When I tried to illuminate the DMD with the light, I found some differences that I would like to inquire you.

Normally the DMD chips have a specific tilt angle. for the DLP 6500, the tilt angle is 12 degrees. If I want to illuminate the DMD with light (DMD is fixed vertically , and the light is coming from the side), I need to tilt the DMD at an angle: arctan(tan(12 ÷ √(2)), then I can get the right reflected light from the DMD (parallel to the building platform).

For the DLP 670s, the tilt angle is 17.5 degrees. According to our experience on setting up DLP6500, we first tilt the DMD and tilt the DMD arctan(tan(17.5 ÷ √(2)), but the reflected light is going upwards instead of parallel to the building platform. The weird thing is that if I don't tilt this DMD, then it could come with a right reflected beam that is parallel to the building platform.

So I am wondering what is the reason behind this difference. why for the DLP670s, it is not necessary to tilt the DMD an angle in our case?

Best regards,

Ben

  • 0
    TI__Guru 54550 points

    Hello Ben,

    Please see the data sheet sections 6.11 and 6.12 for the DLP670S - https://www.ti.com/lit/ds/symlink/dlp670s.pdf.

    This DMD has a different pixel architecture than the DLP6500.  You will need to rotate the DMD shown in your picture 90 degrees counter clockwise to get the reflection direction you want.  It will need to be 35 degrees from the DMD normal to get the "on state" pixels to project normally to the DMD and the dump light will go down to the left.

    Fizix

  • 0
    Prodigy 40 points

    Hi Fizix,

    Thank you for the explanation. Now I understand. One more question, if I keep the orientation of the DMD as shown in the pictures and use the DMD "off state" pixels to refract the light. Are there any potential drawbacks compared to using the on-state pixels (of course we need to invert the design pattern)?

    Best,

    Ben

  • +1 in reply to Bin Wang
    TI__Guru 54550 points

    Hello again Ben,

    Please be aware that there is a border or pixels (usually several wide) around the active array area that are always "off" which will show up as a bright border if you use the reverse orientation. 

    Also in your image the light would have to come from the other side of the DMD since the mirrors in the off state tip to the left side of the DMD.

    Fizix