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DLP9000: Working with pattern mode

Pourya Torabi
Prodigy 180 points

Part Number: DLP9000
Other Parts Discussed in Thread: DLPC900, DLP4500

Hi

I have a DLP lightcrafter 9000, and a dlp 9000 dmd. I'm working with video mode with display port connected to PC. I'm using it for 3d printing application. As I know using pattern mode is more precise than simple video mode. I'm a little confused on how to use pattern mode. Is it possible to use a simple video mode and connect the projector to pc via Display port but the lightcrafter project the images by pattern mode?

 

  • 0
    TI__Guru 54725 points

    Hello Pourya,

    Welcome to the DLP section of the TI-E2E Forums.

    There are a number of different types of pattern mode:

    • Pre-stored pattern mode - Uses patterns that have been pre-stored by the user in parallel flash memory.
    • Pattern on-the-fly mode - Uses patterns from your PC and loads them up over USB and runs them.
    • Video Pattern mode - Uses the RGB 8-8-8 data coming in over the video and re-interprets it per your definition.

    A good example can be found in this the following thread:

    https://e2e.ti.com/support/dlp__mems_micro-electro-mechanical_systems/advanced_light_control/f/94/t/626491?tisearch=e2e-quicksearch&keymatch=gamma

    The current firmware has 1:1 gamma in regular video mode.  Previous versions had approx 2:1 gamma.  The thread showed how to use Video pattern mode to effectively show how to create a 1:1 gamma.

    For a full discussion of how to use Video Pattern Mode, please see §3.6.4 starting on on page 35 of the DLP LightCrafter 6500 and 9000 User's Guide.  You can see from the EVM guide that you can use the incoming bitplane patterns however you would like, so long as the time you allot between frame changes is less than the frame time for the current video stream.

    Fizix

  • 0 in reply to Fizix
    Prodigy 180 points
    Dear Fizix

    Thanks for your reply, I've already read the user's guide but as I understood you should make a pattern every time with the software, But I wanted to somehow connect it to my PC and send images to projector and it shows them with pattern configs.
    What I'm looking for is to send some gray scale images through HDMI to the projector and the projector show them RAW without any changes, and besides I want the DMD mirrors to be in off state for the black part of the image.
  • 0 in reply to Pourya Torabi
    TI__Guru 54725 points

    Hello again Pourya,

    I think there is a misunderstanding of Video Pattern Mode.  It tells the system how to interpret the image data being received over the chosen video port.  It requires it to be connected to a PC or other video source.  So when you say you want to display them "RAW", what do you mean by that?

    Your video card will determine how it is sent, but it is typically RGB-8-8-8, so that a gray scale image (Gray 0 - 255)  will be sent as  R=G=B=Gray level.  If your video card applies a gamma, the DLP9000 will display whatever is sent.  You will need to make sure that gamma is turned off on your video driver.

    Then If the black parts of your image are truly Gray = 0 (i.e. Black), then what is sent will be RGB = 0,0,0.  The mirrors will be off for those pixels.

    Fizix

  • 0 in reply to Fizix
    Prodigy 180 points
    Hi

    OK I think this web page confused me:
    www.instructables.com/.../
    Based on what I understood the diagonal formation is just for 1280*800 resolution, Right?
    So using simple video mode will do what I need. But As I know the mirrors will flip with a predefined frequency even for black pixels, Am I right? If so I want the mirrors be in off state and don't flip, is it possible?
  • 0 in reply to Pourya Torabi
    TI__Guru 54725 points

    Hello Pourya,

    That link is for the DlP4500 DMD and does not apply to the DLPC900 systems.

    Regarding video mode, the mirrors will be perturbed even when in the "off" position (data = 0) for every bitplane change (ie. 24 times per video frame), but if your optics are correctly designed this should never be seen in the projected patterns.

    Just to be clear, in DLP terminology, "flip" would imply changing the state of the mirror to the opposite state (i.e. 0->1 & 1->0). Every time data is changed on the array the mirrors that do not change state are nominally perturbed by the mirror clocking pulse (often called a micro mirror reset) but do not change state.

    Fizix

  • 0 in reply to Fizix
    Prodigy 180 points
    Hi Fizix

    Thanks for your clarification, that was really helpful, just had a simple question:
    I think perturbing will emit some light in my projector, will using pattern mode omit this perturbing? If so will it affect the life of the DMD?
  • 0 in reply to Pourya Torabi
    TI__Guru 54725 points

    Hello Pourya,

    Your optics should be designed to exclude flat-state light (there are structures other than mirrors that are flat in the array).  If so the mirrors that are "off" and will stay "off" during a "reset" do get perturbed, but do not reach the flat state.  Therefore reasonably designed optics will not see any effect from the perturbation of the "reset"

    An effect that you might see is a slight but very brief (single digit µs) ripple in the output of the "on" mirrors that will remain "on".  This will depend on how small your numeric aperture is.  For F#2.5 to F#4 output optics and slightly under-filled illumination you are not likely to see anything.  You will be more likely very small apertures where the illumination aperture and output aperture are comparable in angular extent to experience this short duration ripple.

    Fizix

  • 0 in reply to Fizix
    Prodigy 180 points
    Dear Fizix

    That was a really good explanation, Thanks. I now understand the difference between off state and perturbation but still didn't get my answer, is there any differences between normal video mode and pattern mode regarding mirrors' function?
    One more question, there's an option in pattern setting, DMD Idle mode, is it the same as perturbation or it will change state between On and Off? What are the benefits of it?
  • 0 in reply to Pourya Torabi
    TI__Guru 54725 points

    Hello Pourya,

    The system is designed to use a solid state illumination system in which the illumination can be modulated to create bits shorter than the load and reset time of the DMD.  Therefore the linearity of the grayscale will be a little off for all modes.  This means that for the very short bits, on pixels will be displayed a little too long.  This is not a function of the DMD/DMD µ-mirrors, but of the controller's sequencer.

    1. Video Mode vs Video Pattern Mode:
      1. Video Mode chooses the best sequence to fill the the frame time, but does leave a small overhead of "dark time" (usually done by illumination modulation) to compensate for sync jitter.
      2. Video Pattern Mode chooses the best sequence base on which RGB bits you have chosen to display and the bit depth of the subframes to fill the exposure times you have defiined.  This is similar to the R, G, & B subframes in regular Video Mode. 
    2. DMD idle mode is intended to exercise the mirrors very quickly at 50% on and 50% off.  This is designed for systems that have mirrors that spend a great deal of time in one state or the other (on, off), especially if they are run at high temperatures.  This is to enhance reliable operation of the µ-mirrors.

    Fizix