DIY Video Projector - Page 103

tom1356 · 15th March 2002, 02:28 AM

jjasniew

I would be interested in your panel if you were interested in giving me a hand with getting the other parts I would need to get the quality of picture you show in the ad?
Thanks
Tom

oftheend · 15th March 2002, 06:01 AM

Hello everyone. I found this site this morning, and have read about 95% of the posts from the beginning. After trying the 100" tv based projector, I decided that it would be just a little more difficult and, just a little more expensive to build and actual lcd projector. The tv projector actually worked a lot better than i had expected, but the problem lies in the fact that the finished unit could be mistaken for your kitchen refridgerator (it is that big), the image is always a little blurry, the room HAS to be pitch black, and the throw distance with the two lenses i tried was only about 4-8 foot, which means the monstrosity has to sit in the middle of my living room, blocking part of the picture it is projecting.

So I started brainstorming a couple of LCD solutions. My first idea was the old pocket tv and slide projector. I thought about an opaque projector, but speculated the lighting to the face of the lcd would render the same result as trying to use your laptop in direct sunlight. And of course there is the overhead projector and LCD overlay, but very few panels are availible at more than 640 by 480. (i want at least 1024 by 768). I have not tried any of these, insead opting to search for more info first, which led me here. I have gotten a lot of perspective on the backlighting of the LCD from the previous messages on this thread. (as well as the heat side affect). I applaud those of you who are trying the white LEDs, that seems to have a lot of promise, once developed. I think for my solution i will end up going with the Flourex, or whatever it is.

Anyway my point is that i have a design that i would appreciate some feedback on. I think it is a fairly decent setup, but i could be missing something. The link to the image is below. The projector is divided into five sections, by various stages of the optics. The back section is where the backlighting is located (compartment 1). There are 4 flourex lights, 2 each side, pointing to the back of the projector. This light is gathered and reflected by a concave mirror towards a condeser lens. This lens is sealed onto the compartment wall, allowing no air travel. The lens passes the light through a short tube extending through compatment two. Comparment 2 contains the tube and fiberglass insulating material, to shield compartment 3 from the heat of compartment 1. (note the dead air space between compatments 1 and 2, & 2 and 3.) On the wall between 2 and 3 is a reversed condensor connected to the other side of the tube, againg sealed to prevent vapor transition. Here the light is spread onto the back of the lcd. in comparment 4 the light sould be travelling fairly straigt into the fresnal lens located between 4 & 5. from the fresnal, the light travels to a lens (have a barco crt lens) and hopefully out to make a big picture on the big screen.

Thank you for any helpful advice, and keep the ideas flowing...

http://members.aol.com/modeofdecay/lcdprojector.html

oftheend · 15th March 2002, 06:05 AM

Typed the link wrong in my last post: it is actually

http://members.aol.com/modeofdecay/lcdprojector.html

jjasniew · 15th March 2002, 08:46 AM

Tom - sure, no problem!

Ofteend - So it is true that XGA OHP panels are rare, 14" LCD monitors are rarer than 15", which are fairly common. A little cited fact is that the bigger the aperature (or diagonal of the LCD element), the more light goes through to the screen, ya know, for the same amount of light going in.

It would make sense then, that the best choice for an element would be the 15" LCD panel monitor, because they're popular and relatively inexpensive ($300 for a 15" XGA vs $200+ for a 5 to 7" VGA panel)

Unfortunately, the 15" is too wide (at ~12") for most OHP stages.
Also, getting one apart so that the light can shine through, whilst still keeping it operational, is non-trivial. Unless you're lucky...

However, I have posted a source for fresnel lenses which are bigger than the fresnel in the typical OHP; it would make sense that you could construct a unit that would resemble a "fat" OHP, with maybe a 12.5" stage., which would accomodate the 15" LCD panel.

Others have said and shown that the ideal light source is a point source that's as bright as possible. The ELMO projector I have bears this out; it has an ultrabright (50K lumens) metal halide lamp with an arc length of about 1/2". When running, the thing looks like that box with an alien inside with the light shooting out every nook and cranny.

The ideal design appears to be a point source light of infinite brilliance, with a lens in front of it. The lens collumnates the light so that it's going out at a right angle from the lens surface, for all points on the lens surface, with perfectly uniform brilliance of course. This way, the panel is illuminated equally at all pixels.

One of the design difficulties is dealing with the heat. The ELMO has fan forced cooling, with one of two fans evacuating the entire enclosure AND pulling air through this metal chimney structure within which the bulb is located. So that bulb has a steady stream of cool, inlet air going over it at all times. (Plus, it's like having a little space heater that keeps me warm...)

My recipe for a stunning success, is as follows

1. Get the brightest, as in # of lumens, OHP you can find.
2. Get a 14" LCD panel monitor, that comes apart OK
3. Arrange it so that it works with the OHP.

OR

1. (same as above)
2. Get a 15" LCD panel monitor, that comes apart OK
3. Get a bigger fresnel lens, arrange it onto the OHP so that it works - create the "fat" OHP...
4. Arrange the panel LCD so that it works with the "fat" OHP.

Of course, "arrange it so it works" may be non-trivial...as a few others will attest.

I'm lucky enough to have a good XGA panel. Even so, the aperature, hence the light, would probably be doubled by going to a 14" LCD monitor panel. 15", even more! This is very alluring to me, that I'd chance blowing ~$300 to find out if I can make it happen.

To recap -

- point source ultra-bright light, fan forced air cooled.
- fresnel lens to collumnate the light uniformly across a 12.5"X12.5" stage
- 15" panel that you can arrange so the light shines through.
- projection lens.

That should do it, I think!

ZZZZZZzzzzz....

skilzygw · 15th March 2002, 09:06 AM

jjasniew What is the model # of your elmo projector?

Thanks! Any links on the web of your OHP?

Also I have a question regarding metal halide bulbs. Does someone sell a Lamp like fixture for a metal halide bulb? The problem is i dont know how to wire so I want a pre-made fixture ready to get a bulb screwed in and plugged in to a socket. Thanks!

skilzygw · 15th March 2002, 09:42 AM

In OHP i notice the bulbs are tiny, What kind of bulbs are they and what kind of fxtures do they have? Is there anyway i can buy both the bulb and fixture for my custom box? Links would be helpful! THANKS!

frankbatzen · 15th March 2002, 10:20 AM

Hi,
I had to change my plans somewhat. In order to move the PCB of my 14" monitor out of the path of light I was going to resolder one 45-pin flexcable connection and one 10-pin flexcable connection with longer cables in between. I started on the 45-pin cable and came to the conclusion that for me it is highly unlikely that after completion there would be no adjacent pins with accidental connections between them. It was just a littlebit too tiny and too close together, even with micro-soldering iron and magnifying glass. I think I've read someone did this with a defective Nview panel, though? So maybe you just need to be really experienced.
Now I changed my setup, so that there no longer is the need to elongate the 45-pin connector. The 10-pin connector still has to be elongated and there is no way around this. Luckily on both sides, the display and PCB that is, there are soldering points close to the connectors for each pin of the cable. They are not much bigger, but they are further apart and that does the trick. On the display part the soldering is completed and seems very well done (not tooting my own horn, just telling you it can be done :-) ) I have taken pictures, but they have to be developed. Yes, that is that old non digital technology our ancestors used...

I have a question for you americans: How big exactly are the normal OHP-fresnel lenses in your country? Here in Germany--and I think all over Europe--the are exactly 28,5*28,5cm with "rounded corners". This leads to the fact that my 14" tft (I think 14" tfts are actually 14,1") does not fit on to the fresnel lens completely. There is about one centimeter lost on each side. The overscan gets worse with growing distance between the tft and the fresnel due to the path of light.

jjasniew: Sorry, I can not find the adress you posted concerning the bigger fresnel lenses. Could you repost it, please?

That's it for now

g!zmo

lokost · 15th March 2002, 03:22 PM

oftheend

Even if you decide to stick with the fluorex lamps you will still need some cooling. Contrary to what the specs seem to indicate, you will be surprised at how much heat 4 of those lamps can put out.

oftheend · 15th March 2002, 04:31 PM

lokost:

Yes, certainly. Between the lamps and power supplies, there will be heat. I am planning on using several high output computer fans, heatsinks where possible. I am hoping that by physically insulating the lighting from the LCD, I can reduce the amount of heat transfered to the lcd, allowing quieter, less powerful fans to run. Given the lower temp of flourescent based lamps, this could make a fairly quiet operation.

jjasniew:

As far as using OHP, sure that is the quickest, easiest way to get the results I want, but I still run into one of the main issues i had with a TV based system: Size. The room I plan on using this thing in is not tiny, but it is my living room. Granted one wall is dominated by electronics already, but the other 3 i would prefer to leave to more traditional decorating. So small size and aesthetics are important in my final solution. Thank you for the advice, and if all else fails, I will prob. go that route. (I really want a projector!!).

oftheend · 15th March 2002, 04:40 PM

I ran across this on Ebay:

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=1712032092

A light valve projector currently at $203 (5 hours left), though it does not power up. Could be a steal for someone who can fiqure out whats wong with the 220 volt monster. The thing looks almost as big as a pallet.

15th March 2002, 02:28 AM	#1021
tom1356 diyAudio Member Join Date: Mar 2002 Location: boston	jjasniew I would be interested in your panel if you were interested in giving me a hand with getting the other parts I would need to get the quality of picture you show in the ad? Thanks Tom __________________ My "cult-like" following is accepting applications.

15th March 2002, 06:01 AM	#1022
oftheend diyAudio Member Join Date: Mar 2002 Location: Schenectady, NY	Hello everyone. I found this site this morning, and have read about 95% of the posts from the beginning. After trying the 100" tv based projector, I decided that it would be just a little more difficult and, just a little more expensive to build and actual lcd projector. The tv projector actually worked a lot better than i had expected, but the problem lies in the fact that the finished unit could be mistaken for your kitchen refridgerator (it is that big), the image is always a little blurry, the room HAS to be pitch black, and the throw distance with the two lenses i tried was only about 4-8 foot, which means the monstrosity has to sit in the middle of my living room, blocking part of the picture it is projecting. So I started brainstorming a couple of LCD solutions. My first idea was the old pocket tv and slide projector. I thought about an opaque projector, but speculated the lighting to the face of the lcd would render the same result as trying to use your laptop in direct sunlight. And of course there is the overhead projector and LCD overlay, but very few panels are availible at more than 640 by 480. (i want at least 1024 by 768). I have not tried any of these, insead opting to search for more info first, which led me here. I have gotten a lot of perspective on the backlighting of the LCD from the previous messages on this thread. (as well as the heat side affect). I applaud those of you who are trying the white LEDs, that seems to have a lot of promise, once developed. I think for my solution i will end up going with the Flourex, or whatever it is. Anyway my point is that i have a design that i would appreciate some feedback on. I think it is a fairly decent setup, but i could be missing something. The link to the image is below. The projector is divided into five sections, by various stages of the optics. The back section is where the backlighting is located (compartment 1). There are 4 flourex lights, 2 each side, pointing to the back of the projector. This light is gathered and reflected by a concave mirror towards a condeser lens. This lens is sealed onto the compartment wall, allowing no air travel. The lens passes the light through a short tube extending through compatment two. Comparment 2 contains the tube and fiberglass insulating material, to shield compartment 3 from the heat of compartment 1. (note the dead air space between compatments 1 and 2, & 2 and 3.) On the wall between 2 and 3 is a reversed condensor connected to the other side of the tube, againg sealed to prevent vapor transition. Here the light is spread onto the back of the lcd. in comparment 4 the light sould be travelling fairly straigt into the fresnal lens located between 4 & 5. from the fresnal, the light travels to a lens (have a barco crt lens) and hopefully out to make a big picture on the big screen. Thank you for any helpful advice, and keep the ideas flowing... http://members.aol.com/modeofdecay/lcdprojector.html __________________ Dave Secor

15th March 2002, 06:05 AM	#1023
oftheend diyAudio Member Join Date: Mar 2002 Location: Schenectady, NY	Typed the link wrong in my last post: it is actually http://members.aol.com/modeofdecay/lcdprojector.html __________________ Dave Secor

15th March 2002, 08:46 AM	#1024
jjasniew diyAudio Member Join Date: Feb 2002 Location: Roy, WA	Projector design Tom - sure, no problem! Ofteend - So it is true that XGA OHP panels are rare, 14" LCD monitors are rarer than 15", which are fairly common. A little cited fact is that the bigger the aperature (or diagonal of the LCD element), the more light goes through to the screen, ya know, for the same amount of light going in. It would make sense then, that the best choice for an element would be the 15" LCD panel monitor, because they're popular and relatively inexpensive ($300 for a 15" XGA vs $200+ for a 5 to 7" VGA panel) Unfortunately, the 15" is too wide (at ~12") for most OHP stages. Also, getting one apart so that the light can shine through, whilst still keeping it operational, is non-trivial. Unless you're lucky... However, I have posted a source for fresnel lenses which are bigger than the fresnel in the typical OHP; it would make sense that you could construct a unit that would resemble a "fat" OHP, with maybe a 12.5" stage., which would accomodate the 15" LCD panel. Others have said and shown that the ideal light source is a point source that's as bright as possible. The ELMO projector I have bears this out; it has an ultrabright (50K lumens) metal halide lamp with an arc length of about 1/2". When running, the thing looks like that box with an alien inside with the light shooting out every nook and cranny. The ideal design appears to be a point source light of infinite brilliance, with a lens in front of it. The lens collumnates the light so that it's going out at a right angle from the lens surface, for all points on the lens surface, with perfectly uniform brilliance of course. This way, the panel is illuminated equally at all pixels. One of the design difficulties is dealing with the heat. The ELMO has fan forced cooling, with one of two fans evacuating the entire enclosure AND pulling air through this metal chimney structure within which the bulb is located. So that bulb has a steady stream of cool, inlet air going over it at all times. (Plus, it's like having a little space heater that keeps me warm...) My recipe for a stunning success, is as follows 1. Get the brightest, as in # of lumens, OHP you can find. 2. Get a 14" LCD panel monitor, that comes apart OK 3. Arrange it so that it works with the OHP. OR 1. (same as above) 2. Get a 15" LCD panel monitor, that comes apart OK 3. Get a bigger fresnel lens, arrange it onto the OHP so that it works - create the "fat" OHP... 4. Arrange the panel LCD so that it works with the "fat" OHP. Of course, "arrange it so it works" may be non-trivial...as a few others will attest. I'm lucky enough to have a good XGA panel. Even so, the aperature, hence the light, would probably be doubled by going to a 14" LCD monitor panel. 15", even more! This is very alluring to me, that I'd chance blowing ~$300 to find out if I can make it happen. To recap - - point source ultra-bright light, fan forced air cooled. - fresnel lens to collumnate the light uniformly across a 12.5"X12.5" stage - 15" panel that you can arrange so the light shines through. - projection lens. That should do it, I think! ZZZZZZzzzzz.... __________________ Joe Jasniewski

15th March 2002, 10:20 AM	#1027
frankbatzen diyAudio Member Join Date: Mar 2002 Location: Hamburg, Germany	Soldering of ribbon cables Hi, I had to change my plans somewhat. In order to move the PCB of my 14" monitor out of the path of light I was going to resolder one 45-pin flexcable connection and one 10-pin flexcable connection with longer cables in between. I started on the 45-pin cable and came to the conclusion that for me it is highly unlikely that after completion there would be no adjacent pins with accidental connections between them. It was just a littlebit too tiny and too close together, even with micro-soldering iron and magnifying glass. I think I've read someone did this with a defective Nview panel, though? So maybe you just need to be really experienced. Now I changed my setup, so that there no longer is the need to elongate the 45-pin connector. The 10-pin connector still has to be elongated and there is no way around this. Luckily on both sides, the display and PCB that is, there are soldering points close to the connectors for each pin of the cable. They are not much bigger, but they are further apart and that does the trick. On the display part the soldering is completed and seems very well done (not tooting my own horn, just telling you it can be done :-) ) I have taken pictures, but they have to be developed. Yes, that is that old non digital technology our ancestors used... I have a question for you americans: How big exactly are the normal OHP-fresnel lenses in your country? Here in Germany--and I think all over Europe--the are exactly 28,5*28,5cm with "rounded corners". This leads to the fact that my 14" tft (I think 14" tfts are actually 14,1") does not fit on to the fresnel lens completely. There is about one centimeter lost on each side. The overscan gets worse with growing distance between the tft and the fresnel due to the path of light. jjasniew: Sorry, I can not find the adress you posted concerning the bigger fresnel lenses. Could you repost it, please? That's it for now g!zmo __________________ Die Mittelmäßigkeit pflegt alles zu verurteilen, was ihren Horizont übersteigt.


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15th March 2002, 09:06 AM	#1025
skilzygw diyAudio Member Join Date: Feb 2002 Location: NY	jjasniew What is the model # of your elmo projector? Thanks! Any links on the web of your OHP? Also I have a question regarding metal halide bulbs. Does someone sell a Lamp like fixture for a metal halide bulb? The problem is i dont know how to wire so I want a pre-made fixture ready to get a bulb screwed in and plugged in to a socket. Thanks!

15th March 2002, 09:42 AM	#1026
skilzygw diyAudio Member Join Date: Feb 2002 Location: NY	In OHP i notice the bulbs are tiny, What kind of bulbs are they and what kind of fxtures do they have? Is there anyway i can buy both the bulb and fixture for my custom box? Links would be helpful! THANKS!

15th March 2002, 03:22 PM	#1028
lokost diyAudio Member Join Date: Jan 2002	oftheend Even if you decide to stick with the fluorex lamps you will still need some cooling. Contrary to what the specs seem to indicate, you will be surprised at how much heat 4 of those lamps can put out.

15th March 2002, 04:31 PM	#1029
oftheend diyAudio Member Join Date: Mar 2002 Location: Schenectady, NY	lokost: Yes, certainly. Between the lamps and power supplies, there will be heat. I am planning on using several high output computer fans, heatsinks where possible. I am hoping that by physically insulating the lighting from the LCD, I can reduce the amount of heat transfered to the lcd, allowing quieter, less powerful fans to run. Given the lower temp of flourescent based lamps, this could make a fairly quiet operation. jjasniew: As far as using OHP, sure that is the quickest, easiest way to get the results I want, but I still run into one of the main issues i had with a TV based system: Size. The room I plan on using this thing in is not tiny, but it is my living room. Granted one wall is dominated by electronics already, but the other 3 i would prefer to leave to more traditional decorating. So small size and aesthetics are important in my final solution. Thank you for the advice, and if all else fails, I will prob. go that route. (I really want a projector!!). __________________ Dave Secor

15th March 2002, 04:40 PM	#1030
oftheend diyAudio Member Join Date: Mar 2002 Location: Schenectady, NY	I ran across this on Ebay: http://cgi.ebay.com/ws/eBayISAPI.dll...tem=1712032092 A light valve projector currently at $203 (5 hours left), though it does not power up. Could be a steal for someone who can fiqure out whats wong with the 220 volt monster. The thing looks almost as big as a pallet. __________________ Dave Secor

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