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Brightness of DLP based projectors

Jordanka Tasseva
Intellectual 380 points
Other Parts Discussed in Thread: DLP5500

I would like to have more information on your projectors. As they are based on the DMD technology, does that mean that at the highest frequency of displaying binary images it works at the minimum intensity of light? My question concerns the brightness of the images. If we need to display binary images at up to 5 kHz, is it at an expense of the brightness of the images? Thank you

  • 0
    TI__Guru 54410 points

    Hello Jordanka,

    Welcome to the DLP section fo the TI-E2E Community.

    For DLP Catalog products the chipset you are refering to is the DLP5500 chipset.  When displaying in binary pattern mode this is NOT at the expense of light time (brightness).  During the display of binary patterns the illumination is constanst and the chipset can display binary frames at up to 5,000 frames per second.

    Fizix

  • 0 in reply to Fizix
    Intellectual 380 points

    Hi Fizix,

    Thank you much for your answer.

    What I am concerned about, is that at such high rates, even if working at the full power of the light source, the light energy delivered to the screen will be very low (since you will have the on state for very short time). I want to be sure that it will be sufficient to produce a bright image. In order to compensate for that, I guess that we need to choose a light source with a higher power. In that case, as suggested by the documentation that you gave me a link to, we should consider the thermal resistance of the array and maybe add a heat sink. Is there an integrated solution to this problem - the chip with the sink.

    Thank you very much,

    Jordanka

  • 0 in reply to Jordanka Tasseva
    TI__Guru 54410 points

    Hello Jordanka,

    I the sense you are asking, the answer would be yes.  This is unavoidable.  The total light will be the flux times the time the image is displayed (1/5000 sec).  You can increase your illumination, but you must also ensure that the DMD remains withing the overal temperature and package temperature delta remain within the datasheet specifications.

    Fizix

  • 0 in reply to Fizix
    Intellectual 380 points

    Thank you much,

    Jordanka

  • 0 in reply to Fizix
    Intellectual 380 points

    Hello Fizix,

    I came up to another possible problem that might arise from using a projector for our application. How can be resolved the problem with the focusing if the screen where we project is not perpendicular to the incoming beams but tilted to 45 deg in respect to the incident beams. Like this, points at one side of the screen would be on focus and on other side - no.

    Thank you,

    Jordanka

  • 0 in reply to Jordanka Tasseva
    TI__Guru 54410 points

    Jordanka,

    You will need to design a  system with a tilt and shift lens so that you can setup the optical system in a Schiempflug configuration.  Please see the following links:

    http://en.wikipedia.org/wiki/Scheimpflug_principle

    http://www.cambridgeincolour.com/tutorials/tilt-shift-lenses2.htm

    I hope this helps.

    Fizix

  • 0 in reply to Fizix
    Intellectual 380 points

    Thank you,

    Jordanka

  • 0 in reply to Fizix
    Intellectual 380 points

    Hello Fizix,

    Do you have an integrate "plug and play" solution using the DLP 5500 chipset or we should choose all the components? May I have assistance on designing the projection system. I as well was considering the on-the-shelf projectors using the DMD technology.

    Your replies are much helpful.

    Thank you,

    Jordanka

  • 0 in reply to Jordanka Tasseva
    TI__Guru 54410 points

    Jordanka,

    I show that Digikey still has one "LightCommander" development kit available.  Digikey part number 460-3493-ND.  I would not wait if you want one.  Otherwise you will have to purchase the chipset and "roll your own".  The LightCommander kit is nice because it comes as a complete kit with light engine and lens.

    Fizix

  • 0 in reply to Fizix
    Prodigy 100 points

    Hi,

    I was just about to order the LightCommander for the same reason but is the CEL5500 not an option too? Does anyone in here have some good or bad experiences with the CEL5500 they did like to share?

    Thanks,

    Oline

       

  • 0 in reply to Oline Olesen
    TI__Mastermind 30875 points

    Hi Oline,

    Welcome to DLP&MEMS forum.

    CEL5500 has same functional capability as DLP LightCommander. We will wait for others to share good or bad experience with it.

    Regards,

    Sanjeev

     

  • 0 in reply to Fizix
    Intellectual 380 points

    Hi Fizix,

    I am still considering what would be the application best suited for us - Light Crafter, Light Commander, CEL or Dli4130. Do you think the Light Commander is still available? I haven't found information if the speed of 5 000 binary frames per second is achievable through streaming in real time from the PC or it is, similar to the Light Crafter, for internal patterns - whose number is limited to 96. Also no specifications for the optics was available - like projection range and image size range.

    Thank you for your time,

    Jordanka

  • 0 in reply to Jordanka Tasseva
    TI__Intellectual 2175 points

    Hello Jordanka,

    The DLP LightCommander(TM) was discontinued by LogicPD.  Availability is based on remaining units at their distributors.  The CEL5500 from DLi is a good alternative to consider if the DLP5500 chip set meets your needs.  If the DLP3000 chip set is an option, the DLP LightCrafter(TM) is a good platform to use in your development.

    Best regards, Eric

  • 0 in reply to ELD
    TI__Guru 54410 points

    Hello Jordanka,

    To answer your specific display rate question, the answer is as follows: 

    To reach 5,000 binary frames per second you have to use the internal pattern memory and preload up to 960 (10 x as many as the LightCrafter).

    In real time 1 bit structured light mode it will display up to 1,440 binary frames per second.  This is done by packing your binary frames into the grayscale values for  24 bit (8,8,8)  color video frame at 60 frames per second.  each color is divided up into a binary plane represented by the MSB throuhg LSB.  The MSB of Red is displayed for 1/24th of the 60Hz frame, then the Red MSB-1 then Green and then Blue each for 1/24 of the 60 Hz frame.

    Note:  This means you must prepack 24 binary patterns into an 8,8,8 RGB video frame before sending it to the Controller to display the next 24 binary frames.

    Fizix

  • 0 in reply to Fizix
    Intellectual 380 points

    Hi Fizix and thank you for your explanation!

    Since I need to project at 5kHz different binary frames, for me preloading of 960 wouldn't work, right? (Otherwise, the newly released CEL5500 is capable of storing that high number. On the other side, in structure light configuration, it cannot work decoding prepacked 24 bit frames in 24 binary ones.) So real time streaming can be the solution for us. It seems however that even if the DMD array response time allows for projection at 5 kHz (for CEL) or 4 kHz (Light Crafter), the input interfaces of the projectors impose limitation of actually making use of that speed (for different frames). Specifically...

    1)Light Crafter has as input Mini HDMI (25 MHz clock rate). Am I wrong to think that for resolution 640x480 that gives approximately 81 Hz transfer rate. When prepacking is used, that would allow projection of 81x24 = 1944 binary frames per second.

    2) CEL5500 has as input USB 2 (up to 480 Mbit/s). Prepacking is not allowed in structured light configuration, so the transfer rate is limited to 1562 binary frames per second for 640x480 resolution. (In video mode configuration on the other hand, the projectors doesn't project sequentially all 24 bits/pixel, so the transfer to HDMI would allow for even lower rates).

    My question is, how is one able to overcome the limitations imposed or by the memory of the projector, or by the input interface in order to make use of the maximum speed allowed by the DMD. Is that difficult to be customized?

    Thank you very much for taking time to consider my requests.

    Kind regards,

    Jordanka