DIY Video Projector

[Axeman]

Well, I had a number of engineers look at my LCD screen today, and it doesn't look good. One of the people who looked at it mentioned the coating on a ribbon cable. It looks just like duct tape and it soft to the touch- it goes from the controller board to the LCD itself, and is folded up under the board when the screen is assembled. Turns out this coating is conductive, which means that there is a very good chance that I shorted out a number of components on the board. That sucks.

Do not use the KDS Rad5 unless you're an experienced electrical engineer and you are comfortable rewiring something this expensive. I don't want this to discourage anyone! This is a great project with the potential to create a high-resolution projector for less than 1/6th the cost of a commercial model. Personally, I want to see myren's setup, and a detailed description of his LCD layout, and what he thinks went wrong. MYREN- if you're reading this, PLEASE let us know what the status is on your project. I, like many others, would very much like to know how easy/difficult disassembling a viewsonic panel is so we know whether to attempt it. I now know how depressing having a broken panel can really be.



I am thinking about putting up a DIY home theater page soon- if anyone still would like pictures of the inside of the KDS, i can post them.

Keep up the good work people. Keep the photos coming.

Phil

[jjasniew]

Phil,

Has something happend to your panel to make it dysfunctional? The conductive foam around the cable may be conductive, but not so much as to cause a 'short' - unless it's stopped working for some reason. I'd check the flex-cable push-in connections if its no longer working.

I would think you'd damage it more by chance of ESD handling, than the foam cable protectors touching anything -

I hope you panel works - it'd be quite a setback to have you pull back now! (You may be just once cable away from having something that works!)

[jjasniew]

Someone's selling an Nview Z350 on Ebay. This is a 1024X768 projection panel that's computer input only; no s-video or composite inputs.

You'll need a 4000+ lumen OHP to make this work. (Maybe you've seen the pictures of mine in action? BTW, it aint mine; I'm keeping it, until I hear or see of some definitive "plans" for using a panel display for this purpose)

Right now, it's at ~$80. The seller hasnt mentioned that it's 1024X768 in the advertizement, but I imagine people will find out (outside of this forum).

FYI

[Bitch]

l the lcd+OHP give a good enough picture to see the benefits of an hd signal?

I know crt and commercial lcd projector looks great. Will our setups come any where near that?

You mean the device or the pic?-)
The picture quality depends on your equipment, but basicly unless you have some very piece of **** equipment, you will get very sharp picture.

I had a chance to get 1024x768 OHP panel relatively cheap (same price than my current one was) but the contrast ratio was only 100:1. I'm more intrested in putting a TFT-monitor in to pieces. My panel has started to "fade" (I don't know how to explain it in english, it produces "white spots", effect that starts happening when LCD gets old, my panel I think is over 10 years old or something). Also one pixel has burned in it now.
Myren, did you have problems fitting your whole image of the Viewsonic to the screen? How big is your OHP fresnel (in inches?) Also, is the Viewsonic very-bad-choice or were you just uncareful with it? Have you got the replacement?

[Bitch]

Myren I'll modify my question a bit cause a panel can't be one which breaks when you move it a bit: Is it possible to build something to protect the "ribbon cable" or what ever it was (I have hard time with words I don't know what they mean) ?

[Bitch]

One more question:
I know there are devices you can share one monitor with two computers but is there a device you can share two monitors with one computer (or is it possible to build yourself easily) ? It would be worth while not having to all the time switch the cable.

[jjasniew]

I just got a 640X480 projection panel, an Infocus panel book 550.
I got it because my 1024X768 panel doesnt have Svideo, nor composite input. Also this panel was spec'd at a 25 ms pixel rise and fall time (Tr/Tf). I'm dissappointed with the "smear" it exhibits, on fast moving images.

http://pws.ihpc.net/joejas/projector/pixeling.jpg

The picture on the above link shows what I mean. Most of the image is stationary and shows nicely. However, the paper in Dave's hand is moving, and makes quite a smear as is seen.

What this does is on all fast moving images (i.e. sports, as was mentioned elsewhere) the images become jagged around the edges. Slow stuff appears fine.

I believe this is going to be a common problem, with ALL panels running on "NSTC" - whether they are adapted from a car application, a game application, or a professional panel such as this one. Unless there's some way to correct this by processing the signal in between (as that Viewsonic tv tuner that displays 1024X768 resolution images from regular TV on a computer display)

My Nview Z350 smears similarly, when run at 60 hz refresh. This gets better, but does not dissappear entirely, at 75 hz. At this frequency it's definitely better then this panel I'm watching now, at a 52" diagonal. This panelbook 550 doesnt show as bright on the same projector and of course the Z350's aperature is larger, at 6.5"x8.5". Bigger is better, at least in terms of the "efficiency".

I really cant watch it with the level of motion smearing it has, so, it'll go up on ebay soon.

I recall from years ago, the old cheap projection TVs just had a regular TV screen where they cranked the hell out of the brightness, a lens, a mirror and one of those highly reflective curved surfaces to project on. That curve matched the curve of the tube face...

I wonder if an acceptable projector can be made by using one of the 'flat screen' crt PC displays, but modifying the high voltage so its super bright? Granted, the phosphors are going to die after a while. But -

- You wouldnt have any smearing problems, or pixel size problems, or slow light to dark rates (tr/tf)

- Everyone's going to panels and dumping the monitors, kinda like everyone's going to projectors and dumping the projection panels / OHP combos. So monitors are relatively cheap, compared with panels.

- You can get 17, 19, 21" monitors reasonably. The more sq in of light off the source, the more light on the screen. Who knows?

Maybe a flat screen 21" crt monitor, cranked up really bright, can out perform any of the smaller backlit LCD panel designs being worked on by hobbiests. Without any speed problems, lamp problems, pixel size problems, cooling problems or having to be satisfied with limited resolution.

Anyone on board with this idea? Of course, it would take some significant engineering to "undo" all the stops on high anode voltage any maker of a recent flat screen crt would have put in place, because of "radiation" issues.

Maybe even larger flat screen crt based monitors can be had at less than $300, which seems to be the price everyone is sticking to for the flat panel LCD units. I have found a number of 15" LCD panels for $250, but the 50 ms tr/tf spec on the pixels makes me question using one for display of anything fast. I'm not about to invest $250 to find out - I just bought something twice as fast that doesnt satisfy.

Especially when this 25ms panel I'm watching now does what it does. If it really is the pixels just not being able to go color to black to color fast enough, to keep up with the image motion.

[jjasniew]

I read a few pages back and mr Axeman mentioned that his KDS LCD panel was 11 ms! So forget 50, forget 25, forget 13/17. I think I'll use one of these smiley things to express how I feel

[Myren]

hey everyone.

sorry for my absence. i've been quite busy with this projector in my absence. actually, my entire life is beginning to revolve around this projector, in a serious way.

lets see, where to begin. ah, questions and comments first:

thanks for the info and links lokost and scot_lad! thats exactly what i was looking for. i'm using a pic clone, code compatible with em and all, but 50 mhz, 2k flash ram and $4 a piece. bless ubicom.


xenon bulbs are litearlly the only way to go for extreme high power systems, aka the over two kilowatt range. but they're not nearly as efficient at creating light as metal halides though, so for reasonable powered systems, i'd suggest sticking with high intensity discharge metal halides. they should offer far better everything for this project, except brightness, which is already more than sufficient with a 1 kilowatt bulb.


hdtv signals are a very real possibility, although i'd say its not worth it unless running at least 1024 x 768. the problem is though that theres no dscaler doesnt support any of the hdtv cards out there, and dscaler is the only acceptable tool i've found for tv tuning. that alone keeps me from recommending investing in hdtv gear.


axeman: i'm very very very sorry to hear about your LCD. my condolonces. good luck. way to keep your head up. i'm sorry we had to find out about the rad5 in such a difficult way.


i did have some problems fitting on the proper sized panel. at first i just dealt with not having the whole panel visible, but i found a bigger fresnel that was of similar enough focal lenght.


the viewsonic is quite suitable to this task. it was my own fault that it got broken, it was being transported around in a plastic bag which is in no way suitable. if i'd bothered to build some rigging on my projector to hold the electronics and panel in place i would not have had this problem. and it wouldnt have been that hard to do either.


theres tons of remote control software that allows you to use one computer like you were there from another computer. theres all types of variants, from ones that'll allow you to run programs remotely to ones that it really is like being at the other system. the other low tech option is just a KVM switch, allowing you to connect two computers to a single keyboard mouse and monitor set and switch between the two.


my own indevours are going in insane directions. eventually, i'm hoping to start a basement buisness selling 1080p compliant 3500+ lumen projectors. already got the power autozoom and autofocs down, thanks to the polaroid transducer set. the high end 6000+ lumen systems will be water cooled. all at ~33 dba sound levels. i really cant think of anything i'd rather do than provide the world with cheap high quality displays.

the whole system is kinda dramatically different from everything we've done. for example, there is no light gathering lense before the panel, simply a custom built reflector that should redirect about 91-93% of the light exactly where i want it. i have some home made plotters designed using a decent encoder system for micron level positioning of the lenses. i'm working on custom molds to build my own quieter blower fans which will be integrated into the casing itself along with various sound absorbant materials. i'm planning out a plaster mold to vacuum bag a custom shell for the system. still having some problems with the optical keystone correction system, but the general idea is down pat. theres a lot going into this that i'd be happy to share if anyone actually cares, although i realize that its so divergent in many ways that no one really cares.

i've kind of been avoiding the forums recently, mostly because i feel guilty for trying to make a living off of something that started out so purely DIY. i guess the only thing i can say in my defense is that - in diy spirit - i plan on putting up full detailed plans - start to finish - for DIY'ers and making available the custom reflector that is the greatest obstacle in this whole design. please dont hate me?

thanks
myren

[dwalls32]

Nobody hates anbody!

Bitch - the cheapest way to get two monitors to your pc would be to throw in a second pci video card. Win 98, 2k, Xp, Me all support it.