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Thread: proper rear projection screens needed

  1. #1

    Default proper rear projection screens needed

    I cant find much info on how they work/what they are. Youtube is only flooded with DIY rear projection screens made from ordinary fabric, frosted glass or similar semitransparent film, and one guy with hundreds of videos on his projection screen paints.

    I want to believe there's more to rear projection screens than frosting glass or acrylic or somehow making them semitransparent diffuse or using thin sheets of PVC sheets or similar that leak the light to the other side as well.




    Then there is one UK company that pops up in the very top of rear projection screen search result on google but they have ignored my emails for months now. http://prodisplay.com/products/rear-projection-screens/



    I want to believe there's more to rear projection screens than ordinary fabric, frosted glass or similar semitransparent film because those leave a lot to be desired (I can get into details why they don't work for me if needed) but I can't find much info. Please provide any info you know.

  2. #2
    Join Date
    Dec 2009
    Location
    Laurel, MD
    Posts
    297

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    Rear projection surfaces (like front projection surfaces) are one of those things that's easy to make functional, hard to make good.

    The biggest factors you need to keep an eye out for are Gain and viewing angle. The gain of the material dramatically affects what your output looks like and you want a different gain material depending on the source of your projection. For laser projectors I really like a gain of 0.8 and a medium grey surface. Viewing angle is pretty self explanatory. These folks have very nicely priced materials and also provide an excellent guide to material selection, which explains some of what you're looking for.

    http://www.carlofet.com/uncontrolled...ial-comparison

  3. #3

    Default

    Sure, both gain and viewing angle depend on the material. But those are not my main issues. My issues are these pvc rear screens diffusing/blurring the projection pixels too much and both rear and front screens having a noticeably textured surface.
    I rented one for a day to test it out and show the issue: https://i.imgur.com/Gim3VHY.jpg

    This is not a big deal for large 80 inch or more projection screens as from those viewing distances the blurred pixels bleeding into each other from rear projection or the rough textured surface for both types of screens is not noticeable. But for smaller projections and closer viewing distances it becomes too apparent for me.
    Maybe I am looking in the wrong places and the proper projection screens are not aimed for these use cases. But then, what can I use?


    TI made 4K home projectors possible about a year ago and recently announced 4K pico chips.

    Those pico chips are not bright enough for the projection sizes and viewing distances I mentioned so I want to know what I'll be able to use as a screen when products using them come out later this year/earlier next year. It's frustrating how I can't get any of the projection screen manufacturers to suggest a proper screen to me for such use cases.

    This is important to me because I got an email recently from Texas Instruments that they finally are about to release a 4K portable DLP chip than can also run at 240! fps in 1080p mode. This quickly gave me two ideas for how these chips could be implemented: gaming projectors running games at 240Hz/fps. And it could be made cheaper than current 240Hz monitors.
    But 4K rear projection will be pointless with such PVC screens viewed from such distance.

    Second idea is a 4K version of a personal theater: https://www.youtube.com/watch?v=UslTgWF7fpY This one worked by not using a projection screen and having the user look through the lens at the illuminated DLP chip directly. This is one of the reasons the field of view was so low. I had one myself but sold it because of that. I was thinking of building something similar but with a projection screen instead. I'm sure there will be other companies attempting something similar soon. Here the standard textured diffusing PVC projection screens become even more noticeable as the projection screen will be viewed through basically a magnifying lens and be magnified about 4x. So, any ideas what can be used for a projection screen for these?
    Last edited by piydadorto; 06-10-2018 at 05:10.

  4. #4
    Join Date
    Sep 2014
    Location
    Colorado USA
    Posts
    211

    Default

    Quote Originally Posted by piydadorto View Post
    Sure, both gain and viewing angle depend on the material. But those are not my main issues. My issues are these pvc rear screens diffusing/blurring the projection pixels too much and both rear and front screens having a noticeably textured surface.
    I rented one for a day to test it out and show the issue: https://i.imgur.com/Gim3VHY.jpg

    This is not a big deal for large 80 inch or more projection screens as from those viewing distances the blurred pixels bleeding into each other from rear projection or the rough textured surface for both types of screens is not noticeable. But for smaller projections and closer viewing distances it becomes too apparent for me.
    Maybe I am looking in the wrong places and the proper projection screens are not aimed for these use cases. But then, what can I use?


    TI made 4K home projectors possible about a year ago and recently announced 4K pico chips.

    Those pico chips are not bright enough for the projection sizes and viewing distances I mentioned so I want to know what I'll be able to use as a screen when products using them come out later this year/earlier next year. It's frustrating how I can't get any of the projection screen manufacturers to suggest a proper screen to me for such use cases.

    This is important to me because I got an email recently from Texas Instruments that they finally are about to release a 4K portable DLP chip than can also run at 240! fps in 1080p mode. This quickly gave me two ideas for how these chips could be implemented: gaming projectors running games at 240Hz/fps. And it could be made cheaper than current 240Hz monitors.
    But 4K rear projection will be pointless with such PVC screens viewed from such distance.

    Second idea is a 4K version of a personal theater: https://www.youtube.com/watch?v=UslTgWF7fpY This one worked by not using a projection screen and having the user look through the lens at the illuminated DLP chip directly. This is one of the reasons the field of view was so low. I had one myself but sold it because of that. I was thinking of building something similar but with a projection screen instead. I'm sure there will be other companies attempting something similar soon. Here the standard textured diffusing PVC projection screens become even more noticeable as the projection screen will be viewed through basically a magnifying lens and be magnified about 4x. So, any ideas what can be used for a projection screen for these?
    Back in the late 70' and through the 80's there were very good rear projection screen materials that gave very good image resolution, as stated earlier in this thread, at the cost of reduced transmission off-axis. I still have some of this material rolled up in a tube. It's dark, charcoal in color and made of vinyl material. I don't know if it or it's derivatives are still available. I'll hunt down the tube in the garage and send you a piece if you are interested.
    ________________________________
    Everything depends on everything else

  5. #5

    Default

    Thank you. Keep it for now, the site Prodisplay finally responded. If their screens don't work for me I will let you know. I don't want to waste your time needlessly. If they are poor I will let you know and be glad to try what you have.

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