DIY Video Projector

[ZeCo]

just fixed that projector. $3 on a new fuse and professional service and the "beauty" is working.

Note:
1. Not much difference of quality from the OHP/panel setup.

I was wondering if I could replace its lcd module for a higher quality one (for that the pins to connect to a controllet board must be the same) and on the small part for the lamp if I can manage to do something in there and use MH instead of that low life/lumens halogen lamp (FXL)

I will probably remove the lamps, place a mirror on it and build an outside lamp housing.

That could be a nice "DIY LCD projector upgrade" project hehe

[Xterrian]

I found several posts about parabolic mirrors, but they all talk about using them to focus a light source. Has anyone thought about using one after the LCD? OK, the basic problem is that you can see an LCD with a normal backlight just fine, but when you try to put that through a lens smaller than the LCD, the light sneaks around the edge of the lens so the resulting projection is dim. How about catching all the light from the LCD with a parabolic mirror of the same size as the LCD and then focusing that on the lens? This way much more of the light that gets through the LCD actually gets to the projection lens. You can use those LEDs as your backlight now. Should I draw a picture?

[fender4]

For those of you with OHP's, would you consider the fresnels to be of greater, lesser, or the same quality when compared to a typical page magnifier (Office Depot variety)?

After closer inspection, and an image wash-out problem that couldn't be cured, I realized that my "new" OHP has a very worn-out fresnel. I think someone used an abrasive cleaner on it! I didn't realize this until I compared its clarity to the edges, where I assume the cleaner missed. It is acting more like a diffuser than concentrating lens system.

So, I am thinking about using two page-magnifier fresnels, back-to-back, when I construct the enclosure for the projector. I know it is less than optimum, but so is my current situation. I have e-mailed Inventory Solutions about buying a salvaged fresnel, but I haven't heard back from them.

I am also dealing with Macrovision problems in a BIG way. Nearly any DVD I place in my Toshiba SD-3750 produces the bright/dark pulsing every 10 seconds or so. Not watchable. I guess I'll have to get one of those stabilizers.

Hey dwalls32! Welcome back to the board.

Zeco,
Congrats on getting the projector running. Would replacing the panel AND the circuit be possible? I know that my panel has easily removable/movable components and would be suitable for a retofit job. Unfortunately, it is only 640x480 (nView Spectra C). It might be difficult to find a discrete panel that would be an upgrade AND be compatible with the existing circuit. Good luck.

-f4

[Xterrian]

Here is a link that explains in detail how to build a parabolic light gatherer (telescope). I will be trying this if no one here can explain why it won't work.

[prjctr_builder]

i have found an LCD panel on ebay.com that supports 1280x900something resolution. if i win it and get a dukane OHP, my image is going to RULE, wish me luck!!!!


aleksey

[Gunawan W]

After 8 month since I started this project, mostly I learned, tested and tuned optical thing, because I think optical is the crusial part of the projector and I won't go to the next step before I get the perfect result.
The main problem is: I couldn't focus the whole projected image evenly, when I got sharp in the middle, the outer perimeter was blur, vice-versa.
I think all of this problem called Abberation.

First is Spherical Abberation (For lenses made with spherical surfaces, rays which are parallel to the optic axis but at different distances from the optic axis fail to converge to the same point.), so far I know, to eliminate this problem is:
1. using double convex lens.
2. covering 1/3 to 1/2 of the outer edges of the lens.
3. using two identical lens to perform as single lens.

Second is Chromatic Abberation (a lens will not focus different colors in exactly the same place because the focal length depends on refraction and the index of refraction for blue light (short wavelengths) is larger than that of red light (long wavelengths).), how to eliminate this problem?
-. using achromatic doublet or triplet lens.

Am I right about all of this? Are you facing the same optical problem as mine?
Please tell me how's your projected image look-like,is it sharp evenly? no blur at the edge of the image?
No blue and red shift on the projected image color?
What's kind of lens you're using?

BTW, I'm sorry for water cooling idea, I'm not the first, I did the drawing for my setup and share it with all of you, but if you search "water" on the printable version, you will come up with a long discussion about it.

see you.

[ZeCo]

Originally posted by fender4
Zeco,
Congrats on getting the projector running. Would replacing the panel AND the circuit be possible? I know that my panel has easily removable/movable components and would be suitable for a retofit job. Unfortunately, it is only 640x480 (nView Spectra C). It might be difficult to find a discrete panel that would be an upgrade AND be compatible with the existing circuit. Good luck.

-f4 [/B]

Possible if I build the whole thing by myself (as I planned) and take all of the great optics out from it.

Thing is: For my bedroom, this commercial projector is GREAT. Unless I could replace the module for a higher quality one, Id rather not mess with it. If I could, them Id mess on changing the light source as well and make it to work on the living room.

My bedroom is about 12" and the projector works great for that. It produces about 75" 4:3 screen.

My living room is huge. Its about 40". Enough room to fill the whole wall (8ft tall) and build a huge screen. however, it is not suitable to do it using a 640x480 panel as the pixels are clear visible (unless I rearrange the living room so I can sit a lot further from the screen).


Here are the parts I have so far:
1. A commercial Boxlight 2100 projector.
2. a 640x480 (800x600 compressed) LCD panel from polaroid
3. a Buhl 211 overhead project.

both OHP and projector use FXL halogen lamps.

what can I do for the living room? Well, I can take the OHP mirror, fresnel and doublet lens out of it. Build a lamp housing and find a 1024x768 panel on ebay.

Result: I sell my 640x480 panel and buy a 1024x768 panel.

[multiplexor]

Originally posted by prjctr_builder
i have found an LCD panel on ebay.com that supports 1280x900something resolution. if i win it and get a dukane OHP, my image is going to RULE, wish me luck!!!!


aleksey

it's 1024x768. i started bidding on it. i see you've jumped in on the bid also. damn...heh

[xblocker]

Gunawan,
There are 2 ways to reduce abberations:
1. decrease of lens aperture. (~2,3")
2. achromats or correction lenses
One of my OHPs has an objective with 2 positive meniscus lenses,
crisp sharp image, no viewable spherical abberations.

xblocker

[oftheend]

Fender4:

I don't know what your home theater situation is, but with mine, I have a Surround Reveiver setup for the sound. Of course, this has a video switch built in, and when I hook the DVD player up to the receiver, macrovison is no more. This is because the receiver has like 4 video inputs and one out to the tv(plus vcr rec loop), so there must be circuitry to counter act macrovison built in, but the movie companies probably dont want them to announce this. If I hook up the dvd player to the vcr, there are problems. But put the receiver in the middle, no prob, and the receiver even has a vcr record loop, 2nd vid out, which also does not suffer from macrovision.