intermitent video - what to do in the black parts.

Discussion in 'Projectors, Screens & Video Processors' started by perfo, Jul 15, 2018.

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  1. perfo

    perfo
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    Hello All,
    I'm setting up a video display to project on to my house for christmas and halloween.
    Question - Is this even possible - big display smaller budget

    I now have the projector and looking for a lens but well on my way..
    My question is more general really and that is. I have a PIR detector that senses if anyone walks up my driveway and this triggered a film to be played on a raspberry PI. The projector then displays the few minutes of film then plays a completely black film until the PIR triggers again. I set this up last year with another projector and it worked fine except a problem occurred. After playing for a couple of hours the image went dim. The PJ was a reconditioned one and was meant to contain a new bulb but still maybe it didn't so I purchased a new bulb but the image is no better , ie it is still a lot dimmer than it was, with the original bulb being slightly brighter than my new one. I've checked all the settings etc. A worry came to me. If I play a black film then all the LCD panels will be black and absorbing all the available light. Could this mean they got too hot and damaged them somehow?

    So my question is two fold really ,,,
    1, Should a projector be able to play a black image at full intensity and not suffer any ill effects ?

    2, is there a better way of doing these blacked out sections? Unfortunately the warm up time of the bulbs means I can't turn them off then back on for the display. And I have no way of knowing how many times they will be triggered ie twice a night or twenty times and I've read about turning on and off bulbs being undesirable.

    Any hints or suggestions ?
     
    Last edited: Jul 15, 2018
  2. noiseboy72

    noiseboy72
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    Yeah...
    Shouldn't affect lamp life - the light is not reflected back to the lamp, but the LCD panels do absorb a little extra energy. You are more likely to get scorched panels, but on your new beast, they are so well cooled, I don't think this would be an issue!

    Turning on and off is not a great idea either, as the cycling of the lamp causes more damage than leaving it on. we used to reckon each power cycle was about 3 hours running time.

    Maybe have a a generic movie that plays all the time - maybe your house subtly changes colour during the evening or something similar?
     
  3. perfo

    perfo
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    If there is no problems running it black then I may stick with what I did last year as it pretty easy to get a short film running and when it finishes another film (the black one) runs in a constant loop until the trigger and the primary one runs again.
    The christmas one may be left to run with different scenes though.

    Here inlies another question then, If I switch from four bulbs to two is that the same effect as turning the projector off , for the two bulbs that get turned off. Ie using two for the black bits and four for the main video won't actually save anything on bulb life as I'm stressing the two bulbs that turn off..

    I long for the day I can afford a 4k true laser projector (£99 any time soon :) ) then I understand it will be quite ok to turn the lasers off and on for the shows...

    Interesting you say a power cycle of the lamps equals about three hours of life... Sorta means there's no point having it on for any less than three hours ...hmm unless it means "on ---three hours film --- off" actually means six hours of bulb life gone..
     
  4. perfo

    perfo
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    Interesting this projector (sanyo plc XF45) has a no show button on the remote. I think this turns the LCDs to black so maybe that is a good option ?
     
  5. noiseboy72

    noiseboy72
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    Its rapid and frequent power cycles they don’t like. You get hot spots on the lamps which become failure points. You get about 1000 hours from a set of lamps and these are designed to run all day, so a 3 hour duty cycle is fine.
     
  6. perfo

    perfo
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    Splendid news noiseboy72 ta.
     
  7. Joe Fernand

    Joe Fernand
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    'No Show' with On Screen 'Display' disabled ought to be ideal.

    Joe
     
  8. perfo

    perfo
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    Just have to figure out how to do it from my raspberry pi rather than the remote then.
    Does the No Show actually do anything other than black out the LCD panels ?
    I'm trying to work out if there is an advantage to no show rather than play a black video.
    I've started another thread to try and get any advice on controlling the PJ from a Raspberry PI
    https://www.avforums.com/threads/controlling-a-sanyo-pj-with-a-raspberry-pi.2178649/
     
  9. noiseboy72

    noiseboy72
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    To the best of my knowledge, No show just mutes the video and audio. There's no change to the lamps or cooling.

    The projector can be controlled by RS232 and the control codes are widely available. If you can knock up a quick RS232 interface, you should be home free.
     
  10. perfo

    perfo
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    No probs knocking up the interface. I've found some codes for another Sanyo (included in it's manual) but not a list directly for the XF45. I'll carry on goggling as it has an RS232 port there must be a list somewhere.
    There is also a USB port so not sure which would be best really. Well as long as either work then I'm happy enough.
    I've stumbled upon a programme called PiPresent it sort of does everything I'm after bar the actual codes. I have already written a crude controller my self but the PiPresent thing looks well worth a fiddle with...
     

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