Ideas and questions

[tsnyder41]

What I want to Build: The best projector one can make for the lowest price

Res: 1024x768 or higher
Colors: 16bit or higher
Light: 50000 lumens or higher
Price: $2500 or lower
Screen: 80" or bigger

This is a crude drawing of what I think would be a start. I don't know anything about optics thats why you don't see them in the drawing.

My questions are;

1) Is it possible?
2) Has anyone done it?
3) Is there a better way to what I want?
4) What problems would I run into?
5) How can we do it?

I know I have alot to learn and alot of work to do. So please don't just look me over. Size is not a problem. Right now I have a hole in the wall going into a closet for my current tv. Thanks

Matt

 

[Nexzus]

For $2,500 you can get a pretty decent commercial-quality projector.

 

[tsnyder41]

I think I could make a better projector for 2500 than I could buy for the same price. Maybe I'am wrong. It is a risk just like trying to pull apart a lcd screen.

I could make a projector for $200-400. It would be fun to build and just to see it work. But I would get bored with the output. Then I would sart replacing parts like lights and lcd screens. The output would get better with each mod. I could keep doing this for a long time.

Lets start to make projectors like the sony 12ht with contrast ratios of 1000:1. What would it take really?

 

[ap0the0sis]

tsnyder41,

for $2,500 you can buy a very good condition CRT projector on ebay. You will not be able to build anything better one than that.

as a matter of fact, thats what you drew in your drawing. crt projectors use red, blue, green lamps to project the image.

if you were to build your idea it would cost you much more than the 2500 dollars you would spend on a crt projector. you would need special "red green blue lcds, very expensive, expecially xga resolution", rgb splitters, convergence programs plus hardware and encoders. plus trying to align those lcds perfectly. you just dont know.....

"Lets start to make projectors like the sony 12ht with contrast ratios of 1000:1. What would it take really?"

An engineering degree! you think they got idiots behind a desk designing these things? you need very good lcds maybe even dlps, lenses, lamps, filters, just to much i think.


you should read a little, then decide what you want to do. 50,000 lumens or higher on a projector will probably wash out all the color on the image and give you a really bad burn. Make sure you wear sun lotion.

if any of us had $2500 to spend on a projector i dont think it would be on a DIY projector

am i right??

ap0the0sis

 

[remp]

ap0the0sis

You sure are right.

For a top grade 3 panel system you need monochrome polysilicon LCD's which are not available to us guys. Not that I have seen, and to build a 3 gun CRT projector is beyond the scope of regular DIY.

But if tsnyder41 would give me his $2500 I will try very hard to spend it for him.

First thing I would do is research XGA panels.
You can get XGA panels. You can get good lighting systems courtesy of these DIY guys. You can control your panel via a computer. The big stumbling block is contrast. With a regular projection panel you are looking at 100:1 or 150:1 tops. If thats not good enough you have to consider another option.
If you strip a monitor and assuming you can move the electronics out of the way you could be in the 300:1 to 400:1 contrast range. Pretty nearly good enough for excellent home use but a risky undertaking. We have good info on materials for projection screens

Now you say 50,000 lumens. That is a lot of light. Any reason for so much light with just an 80 inch picture.

You could just buy an XGA panel and a high lumen output OHP. Some of these are rated at 9000 lumens. Certainly give you a good 80 inch picture.

So your dream projector is not too far away. And probably well down on the $2500 budget.

All the info you need is right here. Its not packaged as a set of plans or anything like that but its here. You have to read a lot. Search a lot.

 

[tsnyder41]

50000 lumens is possible. I think that you don't see them in homes because no one is going to make a projector 8 feet x 4 feet and 5 feet and try to sale it. I have seen a projector designed for theme parks that was rated at 100,000 lumens. They said it was so bright that it gave a 3d effect.

I have been eyeing the mac HD lcd display. 21" with a true res of 1900x1200. It cost $3500. I am trying to find out if I could find the maker and model of the lcd it self. I know I said 2500 but I was about to drop 5000 on a 12ht before I came found info on makeing them. I know 21" lcd would need a huge housing for the optics. I would redesign my floor layout if I had to. Just think of the hd image with 50000+ lunens.

Right now I feel like I am drinking an ocean of information with straw. At this moment I am learning about lcd and how they work. Then I will then move to optics. I have been using links off wiki and google.

If I went with the three lcd design, I could just use three full color lcds and run one color to each. But then I would need everything else that goes into a three lcd design. What how many screens does the 12ht have? what are the big boys doing for their design? Maybe one great screen is the right way. I trying to start a brain storm with a different goal.

 

[ap0the0sis]

tsnyder41,

many people are running home theaters with a screen larger than 8 feet and they dont need 50,000 lumens. the average is 2500 lumens. 50,000 is just an over kill. remember you will be in a small room. 100,000 lumens might be ok for a "theme park" but honestly, do you need it? you think you want that in your room? you might burn your house down or the whole block... ) imagine the power consumption of that projector. you might need your own power plant to run that sucker.

i suggest you spend some time reading the DIY Video Projector and DIY Video Projector Part II so that you can realize exactlly how much work goest into making your own projector. Some guys here have been doing this for over a year(s) and they are still improving their designs... its an on going process.

good luck and if you have moneys, go retail.

ap0the0sis

p.s. the bigger the lcd you are running the more powerfull light source you will need. 21" is just way to big. you'll be looking at an 8' foot projector... LMAO

 

[woneill]

Hi Guys,

While the suggestions presented seem outlandish to our experience, they might not be wrong...

A couple of points, though:

1) The reason to use separate red, green and blue LCDs is because a conventional RGB one blocks 67% of the light due to the red, green and blue filters: the red cell blocks the blue and green components, the green cell blocks the red and blue - etc.

Single colour LCDS need to be combined with beam splitters to make all the red light go through the red LCD, all the blue light go through the blue LCD etc.

This is the main reason they are brighter...

2) I would suggest that in many cases, the contrast ratios of LCDs used for the projection panels are not much worse than the ones used in monitors - if you hit the monitor LCDs with the brightness of a projector, you would be operating it outside of its design parameters, and would probably be lucky to get the contrast levels we see on the projection panels.

3) If contrast was a real issue, it would be possible to stack LCD panels together and drastically increase overall contrast - Xblocker found a German projector in the "DIY Video Projector Part II" thread that uses this principle.

4) 50,000 ANSI lumens output would probably project an image the size of a house - on a house, outside in broad daylight. For home use, with home-size screens, 500 ANSI Lumens is bright, 1000 ANSI Lumens would be INTENSE...

Overall, definitely read the forums through - there is much to learn from some awesome people! However, despite our successes so far, we do not yet have ALL the answers!

Bill.

 

[ap0the0sis]

bill,

thats a great idea of using 2 panels to increase the contrast and color of an image. however i would figure you might get image ghosting because of the space between the panels and the light going through them. unless you take the panels apart and put them together (glass to glass).

hmmmm..... thnking



ap0the0sis

 

[woneill]

Hi ap0the0sis,

You would need an arrangement that passed parallel beams of light through the LCDs. In this case, very close proximity is good - but not necessary...

Bill.

 

[remp]

Woneill
******************
Single colour LCDS need to be combined with beam splitters to make all the red light go through the red LCD, all the blue light go through the blue LCD etc.
This is the main reason they are brighter...
******************

The reason they are brighter is better light sources, materials and optics.

There are losses in the beam splitters and combiners and to make up those losses they use very small point source lights which allow much better reflector efficiency and they use much higher light transmission polysilicon material for the panels. And they recycle the 50 percent polarisd light that we loose.

All three points, better light efficiency, higher transmissivity of polysilicon panels and recycling the normally wasted polarised light make the large difference between a DIY effort and a proffesionally designed and built projector. And of course, it shows in the price.

They also use Micro Lens Arrays to give parallel beams throught the panels to give contrast ratios much higher than we can achieve with currently available projection panels.

However what we do achieve is remarkable and even more so considering the low cost price of DIY projectors.

 

[woneill]

Hi Remp,

All the things you mention count, but when the RGB filters on a normal LCD mean that 67% of the light is lost before you start with the MLA technology and polarization recycling, you are starting a long way back on the grid...

The light splitters are not perfect, and recycling polarized light will definitely give a major increase in output (maybe double), but the big kicker really is the fact that each shutter is blocking 2/3 of the light hitting it.

Bill.

 

[remp]

Greetings Woneill

Cannot agree with your thinking there Bill.

If I am reading you correctly you are saying that changing to a 3 panel setup is the main reason for increased light throughput.

You will probably be aware that early 3 panel projectors were of poor performance offering low contrast and low screen brightness.

Furthermore if changing to a 3 panel setup was the whole story one would think they would simply use the cheaper Amorphous Silicon lcd's and get this gain you mention, however manufacturers have not done so.

They have elected to go for the more costly and technicallly difficult Polysilicon material for the panels.

Polysilicon panels are tougher and thinner than Amorphous panels thus offering more light throughput while also offering more saturated colours and better contrast.

I am saying that 3 panel projectors are better projectors today because of a number of important factors not just that it is a three panel unit.
More light throughput of polysilicon panels is obviously a big advance. Better reflector accuracy using a short arc lamp. Recycling the unused light is also a major improvement factor.

Modern projectors are very good and we could do well to study them in greater detail to see if there are aspects that can improve the standard DIY projectors. Not as a 3 panel system which could be too complex for DIY but points which improve a single panel performance.

For example
Can we get full colour polysilicon panels.. .
Can we get panels that transmit more light. Perhaps LCOS with a colour wheel.
Can we recycle unused light economically thus perhaps dropping from a 400 watt MH to a 250 MH.
If so can we utilise the shorter arc in lower power lamps to our advantage in better reflectors.

One of these days our supply of 10 year old projection panels will dry up. Already we are seeing good panels like sharp QA 2500 going from $250 to $500 on Ebay. Invsol-inc has completely run out of Nview Spectra C panels and has only Spectra C's without video ex stock.

Before stocks of large panels dissapear we should be looking for suitable alternatives as the small projector panel guys are doing.

We need to promote these discussions Bill otherwise we are not making forward progress. I dont care if you are right and I am wrong or the other way round. We will just have to agree to disagree. What I do care about is investigating and trying to find something that is better, cheaper, technically good and something we can use to improve projectors.

The man said he wanted the best projector he could get for the lowest price but he has a budget of $2500.
Whats your best suggestion.