DIY Rear Projection TV

[rmccoll]

Here is a update on my projector, like I said before I have recieved my lcd screen. I have started to build the case for my projector its pretty small 12X9X4.

Im using a 50 watt halogen bulb for my light source, but its only for test purposes and after using that bulb I know a 75 or 100 watt bulb may not be enough to light my projector, so I might use one of those halogen worklight bulbs at least 150 watts with a aluminium reflector made from a soup ladel. A condenser lense system from surplus shed will be used to focus the light, this system consist of two lense that are 70mm in dia. it also has a heat filter between the lense to reduce heat. Or I may just might make a system using two PCX lense which will be cheaper.

My projector lense system is still in the works, I have to order a lens that have a focul length of 75mm, since my lcd screen is so small.

I will post some pictures Monday or Tuesday.

[dbc105]

I am curious to see the results from the tiny LCD. If the resolution is good it will make RPTV a lot easier.
David

[Mesuge]

Hi let me ressurect this awsome thread if you don't mind

Just a couple of observations and maybe suggestions:
We have to crack down this design - just imagine a 40-50"
front projection lcd/mh lamp kit by diydisplyes or others under 1k$ that would be a paradise..

In terms of the design - a shinny funnel between the lamp and lcd is a must - I think Hezz utilizes this concept a lot.. and I think it appeared somehow on that old crt-projection tv diagram before in this thread..

Where I'm still at sea is the optics - specifically the small space between the projection screen and inner optics - would small 8-10" lcd help make the trick?

Also, an embeded PC is a must in this application - I'd say that a passively cooled ITX board (small) via epia 1ghz featuring digital TV PCI card and ATI remote are up to the 'average' TV task. For ultimate DVD viewing a dedicated HTPC is necessary though (in my current setup already placed in another room for noise reasons)..

Has anyone come up with a more defined optical setting that we can start with experimenting with these different projection screen materials and move the project further??
thanks

[Mesuge]

I'm sorry - forgot to include a small but important note on the OHP-RPTV version - accidentally I came across the following OHP design thread which might be usefull to JR and others as well:

- If I got it right he's using his LCD up side down because of antireflexive coating and is projecting backwards through a big mirror and it all looks quite similar to the guts of RPTV!

Diagram:


The entire thread:
http://diyaudio.com/forums/showthrea...820&highlight=

- Pls. can anybody comment on the feasibility of this OHP setting for 40-50" RPTV set up mainly in terms of the short distance between the main mirror and screen ..

Btw. another page has nice intro to the RPTV basics and suggests using "sandwich" technology for the screen -> plexi and thin plastic fresnel lens sheeet attached to each other .. that big&thin foldable fresnel has also appeared at some eshop link earlier in this thread and was for cca70usd

RPTV overview&screen detail:

<b>dbc105 &</b> Please post some pictures
<b>rmccoll</b>

[rmccoll]

Here is a picture of the lcd and the controller board, but the picture did not come out clear, I will have to buy another camera that takes better pictures. I'm not sure if this lcd will work, the resolution is great but, it is hard to find lenses that will magnify the lcd enough to fill my screen. The lenses I have found so far will only magnify the lcd to fill a 20" screen which is only half of what I'm looking for. If anyone is looking for 1.8" LCD, I'll sell this one $50.00. I paid $72.00 for it, I still have it's casing, backlit and speaker if you want it, they still work. The lcd will be great for front projection or car tv.

Another idea that has been on my mine is to use Red, Blue and Green LED the superbright ones and hook it up to a RGB source. Then take two mirrors, one vertical and one horizontal that vibrate at the frequency(refresh rate) coming from the RGB source. The LED will be projected on to a screen as one pixel, the mirrors will make the projected pixel fill the screen creating a picture.

[Mesuge]

rmccoll> there has been a suggestion in one old rptv thread to use some of those lenses from photography magnifiers -> they might posses the power to make the transition from small lcd to big rptv..

btw. would you pls. post more images of your set up the picture quality doesn't matter I'm more curious about the actual setting of your project. Thanks

On the OHP/RPTV thingy I got a preliminary response from its author (the german guy) and he will test it over the next week and post some results..

[joe2000chevy]

I have lens asembly out of lcd projectorsa which use three small lcd's these will work for your 1.8" lcd also.

[rmccoll]

Well I'm back from spring break and I got bad news the 1.8 lcd broke the lcd broke from the ribbon cable. I was trying the stand it up and it fell, but I caught the ac adatper cord( the white cord in the picture), when I caught it the lcd fell off. 70 bucks down the drain.

I sold my Psone lcd to buy this one and know I'm going to buy the Psone lcd again because its my best choice.

[dbc105]

Man that is sad. Money has been me hold up. Had to by my daughter another car, then all the car tags came due, suit for a funeral. Seems every week it's been something. I am still wanting to try an OHP displaying on the rear of the screen. You know, initial testing could be done with just the OHP and anything transparent. Get all that done then work on the LCD.
David

[ebswift]

Money's been my holdup too, not to mention time. I'd love to start a project soon. I wish they'd make this thread permanent, and I also wish they'd stop moderating me soon, it's ANNOYING having moderation without any of the promised thread upgrades.