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DLP4710EVM-LC: Is it possible to update the projection image every 1ms?

Part Number: DLP4710EVM-LC
Other Parts Discussed in Thread: DLPC3479

Hi,

I want to project a 1-bit image at a high frame rate with the DLP4710EVM-LC.
I found that images can be displayed at 1440Hz by using 1-bit monochrome mode.

Then, is it possible to update the projected image from the PC at 1440 Hz?
Or, since the transfer rate of HDMI is 60Hz, is it necessary to combine 24 frames into a single image and transfer it?
In this case, projection images are generated every 16ms.

best regards,

murakami

  • Hello Murakami,

    Welcome to the E2E and thank you for your interest in DLP® technology!

    I'm not sure if I understand your question correctly. It's possible to display pattern at 1440 Hz in external pattern mode.

    In 1-bit external pattern mode, the DLPC3479 controller supports up to 60 Hz frame rate (VSNYC). If you want to achieve the maximum pattern rate of 1440 Hz per 1-bit pattern, then you will need 24 1-bit patterns within a frame. In this case, each pattern can be displayed at 0.694 ms (16.667 ms / 24 ), and the number depends on the pre-dark time, exposure time and post-dark time of your design. 

     

    Regards,

    Lori 

  • Hello Lori,

    I'm sorry for the late response.

    Thank you very much for your detailed explanation.

    I apologize for my poor explanation.
    What I want to do is to generate a projection image for each frame and project it.
    With the 1-bit external pattern mode that you mentioned, I can update the projected image at 1440Hz (every 0.694ms), but the image generation itself is every 16.67ms (I need generate 24 images at a time.).
    This is not good for me.
    On the other hand, I would like to generate image (and project it every time it is generated) at high frame rate.
     It is best to be able to generate images at 1440 Hz (shorter than 1 ms), but 720 Hz (1440/2, 1.39 ms) and 480 Hz (1440/3, 2.1 ms) are also acceptable.

    The reason why images are generated every 16.67ms is because the maximum input frame rate of DLPC3479 via HDMI is 60Hz.
    Therefore, is there any way to transfer and project images every 0.694ms (or 1.39ms, 2.1ms) using other methods such as USB or spi?

    Or can the image be projected frame by frame by turning off Vsync ? (no need sending 24 frames at once?)

    best regards,

    murakami

  • Hi Murakami,

    Can you please help me understand what you mean to generate image at 1440 Hz? Do you have a video generator to create the patterns or do you use your PC via HDMI? 

    I doubt there is limit to generate patterns at high pattern rate when you use a PC. 

    Also, what is the pattern type being used, i.e. 1D/2D pattern, horizontal/vertical pattern? Do you have the pattern images that can be shared with us?

    Regards,

    Lori 

  • Hi Lori,

    Thank you for your response.

    I apologize for the inconvenience caused by the bad explanation.


    I want to build a camera projector system like alvarocassinelli.com/.../.

    Ultimately, it is www.youtube.com/watch, but I am not thinking about the system up to this point, and am thinking of projecting images onto a board.

    Specifically, I want the projected image to follow the movement of the board, ideally as if it were printed on the board.

    The system I am building consists of a high-speed camera, a DLP4710EVM-LC and a PC.
    The camera captures the image and  the PC calculates the posture of the board at about 1000 Hz.
    Then PC generates (with perspective transformation) the projection image based on the calculated board posture and send it to the DLP4710EVM-LC.
    The projection image is a 2D 1-bit pattern drawn only in black and white, e.g. like a checkerboard.

    In this case, in the 1-bit external pattern mode, since 24 images are generated and transmitted at once, when the last image is projected, about 15 ms has passed since the image was generated, and there may be an error in the projection.
    On the other hand, it may be possible to generate a projection image by predicting the posture change of the board, but I think it is difficult to improve the accuracy.

    Therefore, by generating and projecting an image for each frame, the time from image generation to projection can be shortened, and I think the projection error can be minimized.

    I think the maximum frame rate of projectors on the market is 240Hz, but I think 240Hz is a bit slow. Therefore, even if 1440 Hz is impossible, I would like to project images at 720 Hz or 480Hz.

    best regards,

    murakami

  • Hi Murakami,

    Thank you for providing the information! I will need to investigate the possibility and get back to you by next week.

    Regards,

    Lori 

  • Hello Lori,

    Thank you for your help.

    Murakami

  • Hi Murakami,

    Thank you for your patience.

    As I mentioned before, in 1-bit external pattern mode, the DLPC3479 controller supports up to 60 Hz frame rate, so the chipset will not be able to achieve 480 Hz or higher frame rate as your application.

    Please refer to the Figure 7-11 above, and it's mentioned in Section 7.3.2.1.2 of the DLPC3479 Datasheet. 

    Regards,

    Lori 

  • Hi Lori,

    I'm sorry for the late response.

    Thank you for your reply.
    I have confirmed the datasheet.
    I searched for whether PDATA_n can be set directly, but it seems impossible.

    Unfortunately, I will give up on using this projector.

    Thank you.

    Murakami