Home made projector!

[Chernobyl]

Fantastic! Thanks Gizmo

Before I post about rebuilding with reversed LCD and the damage , heres some tasters of what it looks like...

If you check the left edge of the projected images you can see the Cyan tint left by the mishap. I'll repair it when I have some other things to do and its in bits again.
Thankfully, you don't notice it while playing games or movies.

The screen is a 5.5ft diagonal OHP screen. I will try a bigger screen once I get the projector finished.
The monitor used is a 22" Iiyama. Its about 1/2 way between me and the screen.

[Chernobyl]

Originally Posted by danrok

IIRC, the knob marked 1 and 2 is for switching between the spare and main lamp. The knob which makes the picture go funny just helps to focus the light from below on to the glass bed - just fiddle until the picture looks good and the spread of light is even.

Cheers Danrock.
Its seems 3M call that knob the colour tone.
I adjust it til it looks how you describe.

[Chernobyl]

Originally Posted by gizmo

I would think that pretty much any oil would catch radiated heat. As far as I know, all petroleums tend to be rather opaque to infrared light (heat). Unfortunately, you have pretty much exhausted my knowledge of such things.

I didnt know that, thanks Gizmo.
If I do liquid cooling, oil it is!
I tried the Tomshardware method of strapping a 80mm fan to the side. The LCD got pretty warm in places, so am back to the galeforce 20" tree bender.

The top of the LCD will definitely need a fan blowing onto it. I looked around for places to mount one for testing. Not a chance, so my next venture is to get the Dark Cover sorted so I can mount the fan in it.

One thing I was blissfully unaware of in the day is how loud the projector is at night. Its sat right next to my ear! (the right position for the temporary screens size). Its not unbearable, just a bit loud when no other noise is in the room. I'm starting to think it might be a good idea to get a big silent house fan and duct air from it to the inside of the OHP and to the LCD top and bottom. Would save on a lot of fans/noise!
When the bigger screen gets invented, the projector will be sat further back and may not be so bad anyway.

There are a few other issues that I will go into later but I have to say, gaming on this is AWESOME!

[woodeirl]

hi there guys i was just reading the article about the projector it really looks the part, i was actually going to buy one when i get the money together but looking at this article i think il be building my own one now...this is really going to be interesting ..........

thanks chernobyl for you time in writing about this project as your knowlege is surely welcome

[Chernobyl]

Hi Woodeirl
Before you decide whats best for you theres a bit more I'd like to tell.

After extensive testing and lot of hard work, I have come to the conclusion that the LCD screen I have is maybe not the best for the job.
I can never get a white to look white on the screen.
Looking at the TomsHardware project, the photos they produced do show white, so I checked my photos and they too show white. Hmmmm
The camera was pointed at the screen in those photos and it has severely over exposed the Iiyama monitors picture. That really bright blue on the taskbar should be the normal Windows Blue!

It seems my camera (and maybe Toms??) adjust the picture a little. My pictures were taken with a Casio QV3000EX and shrunk in size with MSPaint () with its default compression settings. No modification to the picture was made other than pressing save.

To sum up the colour issue, If I am using the projector and nothing else, I am very happy with the colours, but as soon as I look at my monitor, the projected image seems yellowed. I spent a lot of time trying to match the colours between the monitor and projected image and was quite successful. But white always looks yellowish, this takes a bit of the shininess away when you compare the two displays.

Please take my studies with a pinch of salt as they only involve one LCD. Tom seemed quite ecstatic over how bright his image was, so I am inclined to think that my LCD is NOT the best for the job. This is very bizarre as the contrast ratios seemed to indicate that it would produce an excellent white. (I have read more than once that contrast ratio is not the defining measure of how bright it will go. This is the only information I had to work with tho).
For example I have some screenshots of Halflife 2 here. The sky on my monitor is a lovely Blue but on the Projector its more of a murky day. I didnt actually notice that until I checked the photos. (added note: Just realised that the Full screen video controls for Colour adjustment dont make a difference in games, Doh! I need to adjust the second displays Desktop Colour, more to come on this)

Much more research is needed on this. I am extremely happy with the result achieved as it is a HUGE screen and the quality is pretty good.
As time goes on I will try other screens as I come across them. This project was made so nothing is permanent, swapping the LCD out will be a simple task.
On that same point, if anyone has a WORKING LCD without a backlight that they wouldnt mind donating to a good cause , I am more than happy to pay the post and something for your time.
I will post any results I get on these Forums as I have never had a nicer welcome.

More photos to come if I can put the damn thing down

[Chernobyl]

Hi everyone, some bad news!

I put it down long enough today to repair the fault.
After disconnecting the ribbon cable, I buzzed it out with a multimeter and all was fine! I hoped maybe the ribbon had been tugged and created a bad connection, so put it back together.
Sadly the LCD hasnt worked since. I've attached what it looks like.

Antistatic precautions were taken before handling each time (earthed myself). Good care was made to ensure no short circuits. I have disassembled and reassembled a number of times to no avail. I'm sad but not that sad as I was going to try other LCD's anyway. The risk was known, shame it came true.
Good lesson for anyone else wishing to try, buy 2 LCD's

It seems my LCD is very fragile (I imagine others are too).
For now the project is on hold until I get another LCD, any offers will be most appreciated.

Thanks for watching !

[Gizmo]

I'm gutted! I was really getting a kick out of watching how you were doing with this!

Well, here's hoping you get back in action soon!

[Chernobyl]

Cheers Gizmo.
In a way, I'm quite glad it died as I now have to get another LCD
The experience of doing this is worth more to me than having the projector.
I'm an ex electronic engineer and havent worked in the electronics industry for around 7 years as I took a permanent career move to IT. Mind you I've always got a project on the go!
I relish the chance to polish up a bit and try a few new things

As there havent been any gaming photos posted, heres a very fast Quake 3 game!
This was before the colours were tweaked hence it looks a bit muddy on the projected image. I wasnt going to post it, but beggars cant be choosers.
The other gaming photos were deleted as I was going to take some better ones. Oops!


I did a nice tweak to the projector to make it quieter and shove out more air. The fan in the OHP has a fine guard over it. I removed it (see piccies).
This OHP has a open cutoff, so I cant dip my hand in and get sliced.
Careful of this if you do your own mod and make sure wires cannot get caught.

If anyone would like to ask any questions please do. I have many other photos during the making of this. If you can think of any more neat ideas for this project let us know.
I'll try and get up and running again ASAP

Good luck if you try

[Daniel ~]

Really fun to watch! Would have never guessed you could do this at home! Thanks for sharing, I hope there's more to the story!

[Chernobyl]

well.....
I just found an incredible deal. Cant say where cos it might get rumbled
15" TFT for... wait for it...
£0 !!!

haha
Hope they (yes I ordered 2) turn up

[Daniel ~]

Even though that's twice what you were wanting to pay, you shouldn't come out badly on the deal...":O}

[Chernobyl]

Originally Posted by Daniel ~

Even though that's twice what you were wanting to pay, you shouldn't come out badly on the deal...":O}

It would have been nice, collared!

I may have to bite the bullet on this and buy a decent LCD new. Building the projector has made me realise you cant compromise on the brightness at all. Couple this with a fast responding screen and the price starts to go up.
How about this for top class: IIYAMA ProLite E380S
http://www.iiyama.co.uk/include/getdata.asp?6755

For the spec, its a bargan.

Contrast ratio 450 : 1 typical
Brightness 380 cd / m² typical
Response time 14 msec

Thats up there with the good ones. Perfect for games, movies and very bright. The LCD used in the Tomshardware report has a lesser brightness of 320cdm so this should rock!.
Only downside is the cost at £174 inc Vat (I'm skint). It may be cheaper, havent checked much yet.

Thats the new candidate
I'll scout around for a bit to get the best price and then decide which body parts to sell.

[Daniel ~]

I' will enjoy following your discoveries!

[Chernobyl]

Cheers Daniel, here goes...

After doing lots of reading, I've found that determining the best LCD for a projector cannot be done from only the manufacturers specifications.

This is a very good read about how LCDs work.
http://www.behardware.com/articles/498/page1.html
What I found useful from this article is how light intensities are determined and how a better max light intensity isnt always due to a better LCD panel.
The manufacturer specs do not apply to the LCD panel, but to the monitor as a whole.

3 important things that affect light output and are relevant to building a projector:
1) The LCDs 'seethroughness'
2) The strength of the backlight
3) The effect of filters applied to the LCD screen
Non of these useful criteria are given in monitors specification sadly.

Onto the manufacturer specs:
Contrast ratio is the difference between how light:dark the LCD can go. As in the article, if dark/black has a light intensity of 0.5cd/m2 and the max light intensity is 500cd/m2, you have a 500:0.5 or 1000:1 contrast ratio.

Brightness is the max light intensity (known as Luminosity and other things too). Its always measured in cd/m2 or nits (they appear to be equivelant) so is easy to find on the mfr specs.
In the above case it is 500cd/m2.

The black cd/m2 figure is relevant to a projector. This figure is a one of the variables giving the projector its contrast ratio. The lower the better in theory (this is rarely quoted in a monitors spec).
Note: Ambient light in the room will also affect how dark the black looks on the big screen. A projector screen is white and is true black only in complete darkness. In reality, a little ambient light is no problem.

What we dont know from an LCDs specs is how well light passes through the LCD, a valuable point!
There is nothing to say how bright the LCD is, per unit of light from the backlight. When the LCD is switched off, is it clear, slightly opaque or a bit dark? This will affect how much of your OHP light gets to the big screen.


An Example of misleading brightness figures:
to achieve a max brightness of 500cd/m2, a manufacturer can double the backlight power from a Monitor normally having 250cd/m2. This is likely to double the light coming from a dark pixel too so the contrast ratio remains the same while boosting the brightness.
If the original 250cd/m2 Monitor wasnt suitable for a projector, the 500cd/m2 version with the same LCD is not going to be any better.
I dont know which if any of the manufacturers use this technique, from the article on how LCDs work, it appears some do.

Tomshardware wrote a second article about which LCDs can be used for a projector.
http://www.tomshardware.com/howto/20041201/index.html
Its great they have done this, I wonder if they have tested all these models to make sure.

What I have learned:
A high contrast ratio 'should' help in determining a good LCD for a projector. The BenQ has a 500:1 contrast ratio which is quite high amongst all the LCDs available today.
My experience with the BenQ LCD doesnt back this up, so the contrast ratio isn't a trustworthy measure to use on its own for sure. This needs to be considered with the other variables, but these dont necessarily tell you what you need either!

The max brightness in cd/m2 can be improved by increasing the backlight intensity on a not so bright LCD.
This figure is not able to show how well an LCD passes light (the physical darkness of the panel).
Its a potentially misleading figure, buyers beware.

The LCDs black (no light) cd/m2 figure is not always available in the specs. A low figure is a good thing generally, but must be taken in context of a good contrast ratio and high max brightness :
This figure can be made artificially low by the use of a darkening filter on the screen. A filter will affect all levels of light, I have no measurements to show if this is linear though. From the LCD article it appears that some manufacturers use an anti glare filter. Could these be tweaked Monitors with higher backlight on a poor LCD? Food for thought.


How do you choose a good LCD panel?
1) Get a load and try them!
2) Find someone who has done it and get the same or similar to the one they settled on
3) Inspect broken LCD monitors. You can see which LCD panels look clearest for the spec you want? (I wish I had access to new broken panels)

Tomshardware used a Iiyama BX3814UT 15" LCD. This is a slower LCD not suitable for games so a better alternative is needed.
I have just sold my right kidney and bought the Iiyama E380s which is faster for gaming and claims to be a little brighter. In truth the brightness figure may make no difference, the LCD could even be worse. Hopefully I purchased a good projector LCD this time though.
It better work, I cant sell the other kidney!

More to come

ps another thought!
The BenQ LCD panel has a yellow tint to it. You can see on this photo with the LCD switched off and the OHP on. http://www.aoaforums.com/forum/attac...chmentid=11186
This explains why my whites always looked yellow but the image wasnt dim.
I imagine the monitors backlight was designed to overcome the yellow effect, something an OHP cannot adjust enough. (Or the LCD was made yellow to cope with the light source?)
Another plus for doing a visual inspection of the panel.

[Gizmo]

Originally Posted by Chernobyl

Its always measured in cd/m2 or nits (they appear to be equivelant) so is easy to find on the mfr specs.

You are correct.

Originally Posted by Chernobyl

The black cd/m2 figure is relevant to a projector. This figure is a one of the variables giving the projector its contrast ratio. The lower the better in theory (this is rarely quoted in a monitors spec).

Generally speaking, the black level is set on a black bed-sheet pattern (basically no video), with the contrast at minimum, and the brightness control set to maximum. The video amplifier controls internally are then adjusted to yield a light output of one foot-lambert or about 3.5 nit and with a video input signal of some specified level (usually .1v p-p). Depending on the monitor design, there may also be a specified dc input bias, although modern monitors almost universally have a black-level detection circuit to compensate for the dc bias. With this black level established, the white bedsheet (a solid white screen) is then generated to calibrate the light output level at maximum. Note that 1 foot-lambert is actually still a fairly bright screen. If you turn the brightness down to what would normally be considered 'black', your maximum light output will be considerably less than the rated maximum for the device (usually about 25-%-30% less, at least for CRTs). Also note that the generally accepted practice for establishing 'true black' is to turn the brightness to minimum and then start turning it up until you can just see the raster scan (at least on a CRT; I got out of the monitor game before LCDs really started coming on, so I'm not sure how they do it for LCDs, but the same principles should apply I would think).

[Daniel ~]

Very nice work

[Chernobyl]

Gizmo, I agree, similar principals must be used to calibrate LCDs.
I read somewhere that 1 nit on Black is bad for an LCD. About 1/2 nit is what the mfrs try to achieve.

The calibration process inevitably must be simpler for a LCD. Much

I'd create an intelligent response but I've been up all night and just paid for the monitor and am full of glee. Time for coffee
I'm going to make some tin foil finger tips for handling the monitors innards this time. Better go before I babble some more

laterrrr

[Chernobyl]

Lifes never dull !
I had a delivery yesterday. I ran outside expecting the monitor and I got another OHP !! I definitely only paid for one

The new monitor was shipped yesterday so I hope to have the projector working again this weekend.

I read that you can make a stereoscopic projector from 2 OHP setups with horizontal & vertically polarised filters (using polarised glasses too). I'm not sure how I would get a page flipped image out to each projector though. The NVidia stereo drivers output to one video port only. I'll keep my eye open for any advances in this. I have seen hardware devices that convert 3D to stereo but they are quite expensive. You never know, I might make it a project to build a stereo projector at some point. After all, its nearly feasible now!

The first stereo glasses I had were from H3D on a Voodoo2. I've had the excellent E-Dimensional E-3D glasses for some time now and they are really good if a bit heavy. Stereo is a bind if it involves batteries and heavy glasses.
I'm imagining the game coming from in the room and going out into the distance on a projector screen. Mmm.
Maybe time for another thread!

[Chernobyl]

The projector is up and running again, this time its much better!
Quite fantastic
There are issues, I'll do my best to cover them, ultimately it is great.
Piccys to come!

[DiabloAbogado]

Can't wait! I've heard of this project before (someone was trying to sell the plans for it, but by using a TV instead of LCD) and always wanted to try it out. Your info will definitely help work out the bugs! Keep 'em coming!