Switching Projectors

here's a can of worms: Firmware updates for the projectors. If they have USB or Ethernet ports, they are likely equipped to be updated. Some mfrs (Epson) require you to call the support desk before they will give you a download link. Some update procedures are easy, others are contorted. But every projector I have upgraded over the years has worked better afterwards. So ... have a look. (PS - what model #s are using?)
 
Many, or at least some, projectors that turn themselves off when idle can be configured in their menus to not do that. Probably others cannot be so configured. It's worth consulting the manual and/or scrutinizing the setup menus, in any case.
 
Our projectors have a built in "dowser" function. That facilitates a blank screen when waiting for a video to be projected. This function is remote controllable.
Just to keep terminology correct, a dowser is someone seeking water using a divining rod; a douser is an object that extinguishes light (such as dousing a fire). Though, similar to other words, the longer that these two are misused, they will be correct with time.
 
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I wondered if the switching off because of no change was to avoid a ghost burn in like you can get on some CRT’s and liquid crystal displays. Even a true LED monitor display could in theory be susceptible to burn in since phosphors age, and change brightness. I don’t know enough about DLP units, but I think they are a liquid crystal variant with a color wheel timed to give you the illusion of the colors.
 
I wondered if the switching off because of no change was to avoid a ghost burn in like you can get on some CRT’s and liquid crystal displays. Even a true LED monitor display could in theory be susceptible to burn in since phosphors age, and change brightness. I don’t know enough about DLP units, but I think they are a liquid crystal variant with a color wheel timed to give you the illusion of the colors.
I have ZERO knowledge of this BUT I'll paraphrase a post by @MNicolai , perhaps a year ago, when I asked a similar question regarding "Burn in" in various types of more "Modern" displays [ Modern compared to conventional CRT's ]:

I believe @MNicolai mentioned MOST more modern displays were constantly (visually unnoticeably) shifting their images by ONE pixel, up/ down / left / and right to minimize the potential effects.
Perhaps @MNicolai would comment on your post.
Toodleoo!
Ron Hebbard
 
I don’t know enough about DLP units, but I think they are a liquid crystal variant with a color wheel timed to give you the illusion of the colors.

DLP systems do (often) have a color wheel, but the DLP device itself is nothing like an LCD panel in its operation. They consist of an array of itsy bitsy mirrors that can be tilted under electronic control. Tilted one way, they reflect the light from the light source through the color wheel and into the lens system; tilted the other way, it's instead directed away to a light trap of some sort. Different brightness levels for the pixels are achieved using PWM or variable duty cycles, I presume. (There are, of course, a couple other ways of getting color: having more than one DLP array, one for each primary, or having an LED or other light source that can change colors rapidly enough.)

Anyhow, it is essentially immune to burn-in; there's no basic mechanism whereby a ghost image would appear. It would be possible for a given pixel's mirror mechanism to break and make a stuck pixel, but that would be pretty much independent of what image is being displayed since it's operating continually regardless--excepting, possibly, pure black and/or pure white pixels.
 
We are going to use two projectors for different cycs during a new show. The animation clips are running on a laptop with MS PowerPoint (works a lot better then anticipated) . But we are having a problem finding a 2nd computer to accommodate the 2nd cyc. As we are using the two cycs at different times it would seem that we could merely remove the HDMI from projector 1 and plug in HMDI from projector 2. But I am nervous that the projector being switched out will report "No HDMI" as the scene changes and then switch off.
So, question: How could I use one computer to feed a PowerPoint presentation to two separate projectors at different times during the show?
To Robert, Most laptops can only support one external monitor, so getting a 2nd laptop is the best approach. You will only need it during the rehearsal and show times, not 24x7. If you had the time, a desktop PC could be setup with multiple video cards and support a display and two projectors. But that is a whole new project and will require time and resources to setup. Other Ideas and depending on the amount of power and memory you need on the laptop: Some people have retired desktops or laptops in their garages, Check with your local PC User's group for ideas, A laptop could be rented (or rental donated for an ad in program), If you have a local IT support group in someone's company or school - call them, or finally - who do you know that's going on vacation? Happy hunting.
 
Just to keep terminology correct, a dowser is someone seeking water using a divining rod; a douser is an object that extinguishes light (such as dousing a fire). Though, similar to other words, the longer that these two are misused, they will be correct with time.
The douser in projectors is used to blank the screen, but not turn off the lamp. The lamp generally take a while to fully cycle up to full power. The douser (mostly mechanical), lets you turn the light on and off quickly. Check the manual for your model to find out how it interacts with the projection signals. My church projector has a douser, but it required additional controls, so it's not generally used, no blank screens.
 
The douser in projectors is used to blank the screen, but not turn off the lamp. The lamp generally take a while to fully cycle up to full power. The douser (mostly mechanical), lets you turn the light on and off quickly. Check the manual for your model to find out how it interacts with the projection signals. My church projector has a douser, but it required additional controls, so it's not generally used, no blank screens.
Yes, internal dousers will be put in place between the optics of a projector, blocking the light from exiting. In addition, the projector will mute the signal (video black) to prevent more light from escaping. If the projector has a solid state light source such as LED or Laser, it may also douse the light source. For lamped projectors, turning them on and off causes stress on the lamp, shortening the life. Some of the external dousers that are commercially available also have DMX control.
 
A black video with a slowly moving, single pixel is probably all it would take. I'll bet a quick internet search would turn one up for free.
 
To Robert, Most laptops can only support one external monitor, so getting a 2nd laptop is the best approach. You will only need it during the rehearsal and show times, not 24x7. If you had the time, a desktop PC could be setup with multiple video cards and support a display and two projectors. But that is a whole new project and will require time and resources to setup. Other Ideas and depending on the amount of power and memory you need on the laptop: Some people have retired desktops or laptops in their garages, Check with your local PC User's group for ideas, A laptop could be rented (or rental donated for an ad in program), If you have a local IT support group in someone's company or school - call them, or finally - who do you know that's going on vacation? Happy hunting.
My dell laptop dock happily supports 2 external monitors and takes way less space and complexity than running 2 PCs. There are also USB to video adapters
 
Once upon a time, we did not recommend using the 2nd laptop output for use in show projections with our software. However, in the last several years, processing speed has improved relative to video rates and the 'skipping' problem seems to have gone away in new vintage laptops. So, yes, that second output or usb adapter is an option.
 
To Robert, Most laptops can only support one external monitor, so getting a 2nd laptop is the best approach. You will only need it during the rehearsal and show times, not 24x7. If you had the time, a desktop PC could be setup with multiple video cards and support a display and two projectors. But that is a whole new project and will require time and resources to setup. Other Ideas and depending on the amount of power and memory you need on the laptop: Some people have retired desktops or laptops in their garages, Check with your local PC User's group for ideas, A laptop could be rented (or rental donated for an ad in program), If you have a local IT support group in someone's company or school - call them, or finally - who do you know that's going on vacation? Happy hunting.

I'm late to the party, but a run-of-the-mill intel laptop from 2013 onwards should support three total displays through the integrated graphics. it's up to the laptop maker if they actually give you more than one output port, but anything from that era onwards (probably a VGA + HDMI for older laptops) should be able to run both outputs simultaniously.

There are also USB video adaptors, but short of modern HDMI / DP over USB Type C, which are just redirecting internal graphics to that port, one should pick a deity and pray when going that route.
 
A black video with a slowly moving, single pixel is probably all it would take. I'll bet a quick internet search would turn one up for free.

Have a little fun with it!
(i've lightened the pipes a bit for visual purposes, but there's a very good chance this would be imperceptible on the projection screen anyways)

[The old windows "pipes" screensaver, with a custom texture]
 

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To put this to bed now, the show went off without a hitch using SCS and two projectors. Right at the last minute the director wanted something that was going to the rear projector changed to the front. It took about 5 seconds to make the change! Just in case, we put up a black picture with that small purple circle bottom left and had no instances of projectors going off. Thanks for all the help and advice. With Covid we could only have 50% seated and sold out so quickly that we put on three extra matinees and sold those out too! News went around town pretty quickly and a lot of the success was due I believe to those animated backgrounds supporting a great cast.
 

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