I recently discovered these forums while searching for some ideas for making a gaming table that utilizes a projector. I set up a home theater a few years ago and thought that I had done a good job getting the best value for my money, but I had no idea that I could have saved a lot of money building my own projector. This forum is great!
Back to my current project… In the past I would haul my projector over to my brother-in-laws house so that we could use it to project maps on the table for RPG games. It was a pain and I read that it can harm your projector, so I stopped doing it. Thanks to this forum I think I could make another projector that we could keep at his house.
My original idea was to use an LCD projection panel to make a front projection system that would hang from the ceiling and project onto the table. But after thinking about it for a while I believe it would be a lot better to use rear projection from under the table. I would get a used table and embed a piece of frosted glass (or some similar material) in the middle of it to use as a screen. I’d rather not mess with removing an LCD panel from a 15” monitor and then having to use a transcoder to make it compatible with the laptop we generate maps on. Instead, I was thinking about using a 15” CRT monitor and a Fresno lens as a projector. Keep in mind that the image doesn’t have to be great quality and it wouldn’t be traveling very far, so I don’t need a powerful light source. Here are the questions I have:
Would it work? Would the light from a CRT monitor be powerful enough?
How far away from the projection surface would the monitor have to be?
What kind of Fresno lens should I use?
Any suggestions for a better projection surface than frosted glass?
Thanks in advance for your help.
-Josh
Back to my current project… In the past I would haul my projector over to my brother-in-laws house so that we could use it to project maps on the table for RPG games. It was a pain and I read that it can harm your projector, so I stopped doing it. Thanks to this forum I think I could make another projector that we could keep at his house.
My original idea was to use an LCD projection panel to make a front projection system that would hang from the ceiling and project onto the table. But after thinking about it for a while I believe it would be a lot better to use rear projection from under the table. I would get a used table and embed a piece of frosted glass (or some similar material) in the middle of it to use as a screen. I’d rather not mess with removing an LCD panel from a 15” monitor and then having to use a transcoder to make it compatible with the laptop we generate maps on. Instead, I was thinking about using a 15” CRT monitor and a Fresno lens as a projector. Keep in mind that the image doesn’t have to be great quality and it wouldn’t be traveling very far, so I don’t need a powerful light source. Here are the questions I have:
Would it work? Would the light from a CRT monitor be powerful enough?
How far away from the projection surface would the monitor have to be?
What kind of Fresno lens should I use?
Any suggestions for a better projection surface than frosted glass?
Thanks in advance for your help.
-Josh
i think this is a great idea. especially the frosted glass idea. however, i don't think a crt monitor will work. it sounds like you're taking the cheapo ebay projection kit approach where they send you a page magnifier and tell you to "build" a box out of cardboard with the "lens" on one end, and mount the thing on the front of your computer or television screen. believe it or not, this actually works, but the quality is poor. what you are talking about would require you to put the crt on it's back, which i don't think is a good idea. also i think the the distance from the front of the monitor plus the "projector" would have the thing pressed against the underside of your table and you wouldn't have an enlarged image at all. you might as well just press the monitor up against the frosted glass by itself. it would be just as effective. THERE IS GOOD NEWS, THOUGH. before you go crazy hunting down the perfect lcd panel, wiring kit, bulb and ballast, and everything that goes along with building a projector, you should try this idea,anyway, but with a few modifications. don't send some guy $5 plus $3.95 for a "fresnel lens" off ebay. that guy goes down to staples, spends $7 on a pack of 5 page magnifiers, and sells them individually. instead, you go to staples, buy them yourself, and build that enclosure. only build it for your laptop. since you're using your laptop anyway, why not just build that setup. you've got your backlight and you're lcd already. in any other circumstance i wouldn't suggest building a projector that way, but i really think it may work for this application. if it doesn't, you're only out $7 and some cardboard.so ridiculous it might work if it does work, you can always upgrade to some mdf or actual wood. hope i was helpful and that other people who have better ideas than me have advice for you also. one last thing: you could probably get away with taping a large piece of drawing or tracing paper to the underside of a glass table, instead of, or until you hunt down the frosted glass. as long as it's opaque it should work.
Thanks for the response eelai. One thing I forgot to mention is that I already have access to several crt monitors (some of which are trinitron/flat screen) and an OH projector, which I can easily take the Fresnel out of. I also do stained glass, so I have frosted glass already. I held a piece of the frosted glass in front of my factory built projector and it really looks very good.
I’ve done a little testing with the fresnel, frosted glass and crt monitor and the image on the frosted glass is blurry. I believe that I’m going to have to change the focus of the monitor, so that the focal point is about 6 inches out from the monitor screen, that way the picture will be in focus when it hits the frosted glass. Does this sound right?
I’ve done a little testing with the fresnel, frosted glass and crt monitor and the image on the frosted glass is blurry. I believe that I’m going to have to change the focus of the monitor, so that the focal point is about 6 inches out from the monitor screen, that way the picture will be in focus when it hits the frosted glass. Does this sound right?
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