Hi, I just signed up yesterday.
I looked through about 30 projects, in plog forum and other forums, and decided that I don't want a wooden case. They look too bulky to my taste and lack the modularity and adjustability I want (sure, some people have made nice cases with adjustable settings but I lack the equipment and experience to do such things)
So I decided to go with a metallic case, probably aliminium, very much like a computer case. I said modular above; I'd like to build something which can be modified and changed easily later. So I'm drawing my own design, and sometime soon I'll have metal plates cut and start the construction.
Note that I haven't even bought one part for the projector since I haven't decided which 15" LCD Monitor to go with (I'll probably buy one in a week or two) and I can find all the necessary parts from a home-construction-store nearby any time (additionally I don't want to handle shipping for the kit from LL, customs bend you like a kinky girl over here). I'd like to share some design ideas and get feedback before doing anything for real.
Nothing is final right now; I decided to use a slot based system for installing the pieces. I'll explain along images.
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The 2 types of plates above will form the slots. As in the image, many plates of "Slot Leaves" will stand vertically on both sides within the case. The little plates, "Slot Bases" will placed between each slot leave. When lined as such, the 2 types of plates together will form the slots, as you can see in the image below.
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There will be long iron bars, about 5mm in diameter, which will go through the holes on the plates to align them perfectly. The iron bars will be fastened on the front and back panels ( not shown here ) to hold the plates firm.
I plan to have the plates 1-2 mm deep, either both plates 2 mm, or "leave" plate at 1, base plate at 2 mm. They will look like these (below image) when secured in the case.
Click to view attachment
What these slots are for? I plan to have all the main parts ( lenses, fresnells, LCD panel, the glass and the lamp ) attached to frames which then can be placed in any slot, thereby allowing a fast slot-adjustment of 3 to 4 mm., and additional more detailed adjustment by the screws on a frame.
For each part, there will be at least to plates. One is the metallic frame I mentioned above. Another plate is the frame cover. Look below.
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Holes are for screws. If you haven't noticed; the frame plate is wider than the cover plate. The extra area on the frame plate, beyond the big screw holes on the corners, will go into the slots and there will be just enough room for the cover plate to be tightened to the frame without obstructing the placement.
LCD Panel and each fresnell will be placed between these 2 plates. I'll cover interior sides of the plates with thick sticky rubber tapes (kind of which is often used in windows) to firm the fresnells. This should also absorb some shock.
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I'm not sure how to handle the LCD Panel though; I fear that the pressure might be too big if I do with LCD like fresnells; compressing the panel between the rubber tapes. I'll probably have the panel rest on rubber cylinders around the screws on the bottom of the plate, and have additional protection from the rubber tapes on the sides. I'll know better when I get the panel naked in my hands.
Placing the frames in the slots
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Click to view attachment
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This is how I plan it to be. The frame plate which goes into the slots will be just about 2mm deep, just enough to go into the slot and stay tight. I plan to have a similar thing for the lamp. Look below.
Click to view attachment
The reflector will sit on the first, bigger plate, but the won't go through it. The plate in the middle will be practically compressing the reflector between itself and the bigger front plate. And the same logic applies to the 3rd plate, which compresses the ceramic between itself and the middle plate. Each plate is supported by 4 big screws. This should hold the lamp setup pretty tight I think.
That's all for now, don't worry about light reflecting and leaking through the slot leaves and that empty spot between the base plates. Additionally, there will be shielding for the heat and light, I'll introduce those elements later, if no one manages to find a critical issue with my designs.
What else you should know.. Basically the case will be a large plate for the bottom of the case with a metalic skeleton built on it. Slot plates will sit on the bottom and be tightened by the iron bar going through them, which will be fastened to the skeleton. And finally there will be covers for the skeleton, using a material name of which I don't know in english. It's the same material used for covering the case in regular computer cases.
One serious issue could be the weight I guess. The slots look much like a heatsink (and I also expect them to act like one), but we all know how much the heatsinks weigh. I may decide to have seperate "slot leaves" for top and bottom, like the base plates for the slot. But that will probably bring its own issues.
What do you think?
Full Version: denizsi's Pre-Plog
I wonder now, was this the right forum to post all that stuff I wrote above? Anyway, I forgot to mention; what should be the measures of the frame plate's window, where the light will go through? I'll be using a 15" LCD as I mentioned before. If there's anyone who'd like to help, I'm in need of it now.
G'Day denizsi
I notice you're planning on mounting the globe "aiming" directly into the projector. I haven't seen it done this way before - other plogs show it mounted perpendicular to the light path.
Have you seen any other results using this technique? It looks like an easily adjustable way to mount the globe & reflector.
I notice you're planning on mounting the globe "aiming" directly into the projector. I haven't seen it done this way before - other plogs show it mounted perpendicular to the light path.
Have you seen any other results using this technique? It looks like an easily adjustable way to mount the globe & reflector.
From what I've seen on others' PJs, this usually causes a hotspot but I'm hoping to prevent that by using an iris in front of the lamp and maybe using an oval-to-rectangular reflector. I don't know yet but I'm not worried about it, slot-and-frame seems very flexible (on the paper that is), so hopefully I'll be able to change it later accordingly.
I measured the thickness on my Fresnel lenses with a digital calipers. 2mm and 2.3mm. My LCD came in at 2mm. You might want to measure your fennels and LCD, to make sure that all will fit. Also, with such tight tolerances... 0.00, you might have to investigate "coefficient of thermal expansion".
Coefficient of thermal expansion @ Wikipedia
You don’t want to have your LCD glass expanding faster than the slot...
Perhaps if you went with a 3mm spacing, and a dab of a non conducting non-hardening glue/caulk/tape to hold things in place and keep them from rattling. Do some experiments first to make sure your solution is reversible and non conductive.
This isn't my field of expertise, but I remember back to my physics classes where we measured expansion in aluminum rods due to heat and cold... It was significant enough that with a ZERO tolerance application you need to be aware of it to make sure your rack expands faster than your components.
Perhaps one of the more experienced users can comment on LCD - Fresnel spacing and its effects. You may be out thinking the problem and over engineering it.
I did like your idea, it got me thinking enough to do a first... post to someone else's plog.
Disclaimer. None of the above is intended as a flame.
Coefficient of thermal expansion @ Wikipedia
You don’t want to have your LCD glass expanding faster than the slot...
Perhaps if you went with a 3mm spacing, and a dab of a non conducting non-hardening glue/caulk/tape to hold things in place and keep them from rattling. Do some experiments first to make sure your solution is reversible and non conductive.
This isn't my field of expertise, but I remember back to my physics classes where we measured expansion in aluminum rods due to heat and cold... It was significant enough that with a ZERO tolerance application you need to be aware of it to make sure your rack expands faster than your components.
Perhaps one of the more experienced users can comment on LCD - Fresnel spacing and its effects. You may be out thinking the problem and over engineering it.
I did like your idea, it got me thinking enough to do a first... post to someone else's plog.
Disclaimer. None of the above is intended as a flame.
QUOTE (denizsi @ Dec 8 2005, 06:27 AM) 
From what I've seen on others' PJs, this usually causes a hotspot but I'm hoping to prevent that by using an iris in front of the lamp and maybe using an oval-to-rectangular reflector. I don't know yet but I'm not worried about it, slot-and-frame seems very flexible (on the paper that is), so hopefully I'll be able to change it later accordingly.
With my commercial projector, the hot-spot is more dependent on the surface your projecting on. Latex white gloss vs. flat white. When I painted my wall with flat egg shell white, the hot spot went away.
denizsi: Your slotted sled seems sound as long as you allow yourself room for flexibility when fine adjustments are made upon final projection.
What I'm more interested in is your light engine. It is true that we are building high res projectors, it's the issue of the lack of projected lumens that we are trying to achieve most out of our lamps. Aside from LuckyMe who is using his Ushio and his parabolic reflector your the second builder who as considered aiming the bulb towards the panel. Previous builders here have been very busy trying all sorts of ways to improve even lighting thru out our projection and direct more light up to the screen even as far as removing the antiglare from our panels just to make it more transmissive. Although, finally the Pro lens that was developed now fixes this, we who are still using the standard lens are still working with new ideas.
We would be most interested to see how your engine works for you.
This iris your referring to would it be a precondenser lens or is it a light gate?
sim
What I'm more interested in is your light engine. It is true that we are building high res projectors, it's the issue of the lack of projected lumens that we are trying to achieve most out of our lamps. Aside from LuckyMe who is using his Ushio and his parabolic reflector your the second builder who as considered aiming the bulb towards the panel. Previous builders here have been very busy trying all sorts of ways to improve even lighting thru out our projection and direct more light up to the screen even as far as removing the antiglare from our panels just to make it more transmissive. Although, finally the Pro lens that was developed now fixes this, we who are still using the standard lens are still working with new ideas.
We would be most interested to see how your engine works for you.
This iris your referring to would it be a precondenser lens or is it a light gate?
sim
Thank you all for the input.
Unwin, I must admit that thermal expansion never occured to me. So I'll probably do as you said; leave 3 mm for slot and the frame will be 2 mm. I can always use rubber tapes to prevent the frame from moving. Thanks.
I won't be doing anything before I get my LCD, but regardless, I plan to have at least 2 mm between the edges of a cover plate and the slot plate, in an installed position.
SIMUL8R, the iris I'm referring to is either only a light gate, or kind of both. I got the light gate idea from SamuraiJack's plog. I'm thinking about putting a light gate right infront of the heat glass, and attach a lense onto the light gate, a smaller negative fresnel perhaps, if I can find one. I'm hoping this will allow a better light projection. I don't know how much extra space all this will require but like I said before, everything's on the paper now.
What still concerns me most is the weight. I'm thinking about applying the same design to MDFs.
Additionally, I'm also looking into pun1sher's latest design ie. improving it for easier montage/demontage. I'm working on a few other designs as well, and one of them is similar to pun1sher's, except that there is only 1 slot for each component (unlike the heatsink-like model I posted here) and the slots are the only screw-mounted ones. I'll still be able to mount/demount frames holding the lenses, lcd and lamp with ease according to the plan, I will mspaint it too tonight.
Unwin, I must admit that thermal expansion never occured to me. So I'll probably do as you said; leave 3 mm for slot and the frame will be 2 mm. I can always use rubber tapes to prevent the frame from moving. Thanks.
I won't be doing anything before I get my LCD, but regardless, I plan to have at least 2 mm between the edges of a cover plate and the slot plate, in an installed position.
SIMUL8R, the iris I'm referring to is either only a light gate, or kind of both. I got the light gate idea from SamuraiJack's plog. I'm thinking about putting a light gate right infront of the heat glass, and attach a lense onto the light gate, a smaller negative fresnel perhaps, if I can find one. I'm hoping this will allow a better light projection. I don't know how much extra space all this will require but like I said before, everything's on the paper now.
What still concerns me most is the weight. I'm thinking about applying the same design to MDFs.
Additionally, I'm also looking into pun1sher's latest design ie. improving it for easier montage/demontage. I'm working on a few other designs as well, and one of them is similar to pun1sher's, except that there is only 1 slot for each component (unlike the heatsink-like model I posted here) and the slots are the only screw-mounted ones. I'll still be able to mount/demount frames holding the lenses, lcd and lamp with ease according to the plan, I will mspaint it too tonight.
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