muzzman: actually, what would be ideal is to be able to have your contrast, brightness and volume settings all depend on the brightness of the scene. i started working on that a month ago - after picking up the DScaler source - and have been making fickle progress when i get enough time to code it.
that way you can custom tune the light and dark scenes and gradient between them. with gamma, if you've got a really dark scene, everything suddenly would jump up a fixed amount. with gamma a really bright scene would suddenly become not so bright. by fine tunning the gamma contrast and brightness (or beter yet, just do a photoshop style curves editing) for each scene, you can find something that looks good everywhere.
i think its the only way were gonna get decent pictures on both light and dark scenes without the high gain screen that are otherwise necessary to make em beautiful.
dont really have any EFFECTIVE ways of checking sccreen brightness, sadly.
myren
that way you can custom tune the light and dark scenes and gradient between them. with gamma, if you've got a really dark scene, everything suddenly would jump up a fixed amount. with gamma a really bright scene would suddenly become not so bright. by fine tunning the gamma contrast and brightness (or beter yet, just do a photoshop style curves editing) for each scene, you can find something that looks good everywhere.
i think its the only way were gonna get decent pictures on both light and dark scenes without the high gain screen that are otherwise necessary to make em beautiful.
dont really have any EFFECTIVE ways of checking sccreen brightness, sadly.
myren
Reflective panel?
I just had a thought.
Has anyone tried putting a mirror behind an LCD panel and shining light on the front? Sure, it means that you will lose 50% of the light, and it would be a pain in the a**, it would solve the problems those of us with ribbon cables are facing. If you put a mirror and fresnel together, you could focus the light back up to an OHP head and still slide the whole thing under any PCBs.
Doesn't do me much good until I get a new monitor/take mine apart again and try to fix it(shudder).
I just had a thought.
Has anyone tried putting a mirror behind an LCD panel and shining light on the front? Sure, it means that you will lose 50% of the light, and it would be a pain in the a**, it would solve the problems those of us with ribbon cables are facing. If you put a mirror and fresnel together, you could focus the light back up to an OHP head and still slide the whole thing under any PCBs.
Doesn't do me much good until I get a new monitor/take mine apart again and try to fix it(shudder).
Screen brightness
Myren,
Check out this http://www.barco.com/projection_systems/customer_services/advice.asp to measure screen brightness...
Nick, I'd post it to you, but it belongs to my employer! Luckly, I didnt make the mistake of buying it, just borrowed it to check out.
Axeman, well, they DO make OHPs where the light is on top (up with the lens assy) it shines down on a fresnel with a mirror behind it, then bounces back up through the lens to project an image of whatever "foil" you have placed on the stage.
Here's a like to show what this type looks like - http://www.dynadirect.com/bc-apovs3000.html (3000 lumens)
Putting the light up top solves a lot of cooling and noise problems, provided the bulb can operate being only convection cooled.
So its is logical that if you can sandwich a fresnel and a mirror just behind the LCD, that arrangement might - just might - be similar enough to a "foil" on top of the stage of the projector in the above link! The large aperature from the 15" LCD panel display might (again, just might) allow you to use a 3000 lumen unit with a satisfactory screen brightness.
Great idea!
Myren,
Check out this http://www.barco.com/projection_systems/customer_services/advice.asp to measure screen brightness...
Nick, I'd post it to you, but it belongs to my employer! Luckly, I didnt make the mistake of buying it, just borrowed it to check out.
Axeman, well, they DO make OHPs where the light is on top (up with the lens assy) it shines down on a fresnel with a mirror behind it, then bounces back up through the lens to project an image of whatever "foil" you have placed on the stage.
Here's a like to show what this type looks like - http://www.dynadirect.com/bc-apovs3000.html (3000 lumens)
Putting the light up top solves a lot of cooling and noise problems, provided the bulb can operate being only convection cooled.
So its is logical that if you can sandwich a fresnel and a mirror just behind the LCD, that arrangement might - just might - be similar enough to a "foil" on top of the stage of the projector in the above link! The large aperature from the 15" LCD panel display might (again, just might) allow you to use a 3000 lumen unit with a satisfactory screen brightness.
Great idea!
A colleague shared this link for DIY CRT projector.
http://www.do-it-yourself.netfirms.com/projector.htm
http://www.do-it-yourself.netfirms.com/projector.htm
Attachments
Portable ohp:s (light at top, mirror or such reflecting the light back to the lens) don't work with LCDs. Although I have got no experience on this, I've read about it.
I got my screen mounted today. It's quite cool, although it doesn't work with ambient light as the ambient light shines quite badly on it which sucks *** a bit. But it's movie screen anyway and works ok lights off. I get 120" (measured from top left to bottom right, does "diagonal" mean this?) windows deskktop on it.
There's still loads of stuff before I'll get happy with this. Firstly I need get that damn VGA Y-cable. Secondly I have some minor problems with the ohp cooling (it gets _hot_ and the thermal switch thing doesn't work on it so it won't cool it after you turn it off, so I have to open the "hatch" after a session). Fixing it wouldn't cost much but I just can't get around to take it to be fixed.
I would definetly want new LCD with better contrast and res. With 15"-lcd the image would get almost twice as big which normally I quess would be just good but it wouldn't fit to the screen/wall and there's no way the ohp is going to be at the middle of the room. But buying Viewsonic or such won't anyway happen before the price drops to reasonable level.
At least for now I would want to disable/lower the rpm of the cooler of the current LCD as the noise is just terrible.
Oh and then there's that DVD-decoder card still to get to improve the movie quality and blaablaablaa..
I'm up to bed.
I'll watch some movie tomorrow and see what are the feelings after it..
I got my screen mounted today. It's quite cool, although it doesn't work with ambient light as the ambient light shines quite badly on it which sucks *** a bit. But it's movie screen anyway and works ok lights off. I get 120" (measured from top left to bottom right, does "diagonal" mean this?) windows deskktop on it.
There's still loads of stuff before I'll get happy with this. Firstly I need get that damn VGA Y-cable. Secondly I have some minor problems with the ohp cooling (it gets _hot_ and the thermal switch thing doesn't work on it so it won't cool it after you turn it off, so I have to open the "hatch" after a session). Fixing it wouldn't cost much but I just can't get around to take it to be fixed.
I would definetly want new LCD with better contrast and res. With 15"-lcd the image would get almost twice as big which normally I quess would be just good but it wouldn't fit to the screen/wall and there's no way the ohp is going to be at the middle of the room. But buying Viewsonic or such won't anyway happen before the price drops to reasonable level.
At least for now I would want to disable/lower the rpm of the cooler of the current LCD as the noise is just terrible.
Oh and then there's that DVD-decoder card still to get to improve the movie quality and blaablaablaa..
I'm up to bed.
I'll watch some movie tomorrow and see what are the feelings after it..
Maybe, Maybe not
Bitch,
They dont work with an ordinary projection panel, because the panel puts some space between the bottom protective glass and the LCD - usually for air cooling. On top of that, the panel has feet which further lift the LCD up above and away from the reflective surface.
Axeman was thinking of putting the reflective part right up against (in physical contact with) the LCD element itself, which may or may not make all the difference.
Also on my panel there is a top glass, with another space between. Certainly all these glass panels and spaces are going to ruin the original operating principle; hence why the ordinary situation doesnt work!
Bitch,
They dont work with an ordinary projection panel, because the panel puts some space between the bottom protective glass and the LCD - usually for air cooling. On top of that, the panel has feet which further lift the LCD up above and away from the reflective surface.
Axeman was thinking of putting the reflective part right up against (in physical contact with) the LCD element itself, which may or may not make all the difference.
Also on my panel there is a top glass, with another space between. Certainly all these glass panels and spaces are going to ruin the original operating principle; hence why the ordinary situation doesnt work!
reflective panel
Axeman,
Long ago I did experiment with small lcd panel calculator.
The panel has reflective surface right behind it.
I put the lamp (300w halogen floodlight) in front of the panel (slightly above), the light beam shone the panel and reflected to the lens right in front of the panel and I can saw the image on the screen. This setup basically is opaque projector. Can't do it with larger panel, because my PS1 panel was broken. If this setup can really work, it will help us a lot.
see you.
Axeman,
Long ago I did experiment with small lcd panel calculator.
The panel has reflective surface right behind it.
I put the lamp (300w halogen floodlight) in front of the panel (slightly above), the light beam shone the panel and reflected to the lens right in front of the panel and I can saw the image on the screen. This setup basically is opaque projector. Can't do it with larger panel, because my PS1 panel was broken. If this setup can really work, it will help us a lot.
see you.
I like the idea of the reflective LCD for the sake of simplicity, but in my opinion, I think this approach may present a few problems. If I understand the concept correctly, the light will need to enter the LCD and strike the reflective surface at some anygle other than perpendicular to the LCD so the light source isn't obstructing the reflective image. This should be possible if the pixel size is relatively large because the chances of the entering light and exiting light striking the same pixels will be higher. However, with higher resolution LCD, the pixel size is usually relatively small. This could lead to the light striking one pixel as it enters the LCD, reflecting at an angle, and striking a different pixel as it leaves. This would probably give the impression of lower resolution.
This may not be the case, so don't let it discourage anyone from trying it. It would definitely allow the use of many displays that were previously unusable for this purpose, and I am very much in favor of that. Does anyone have any ideas concerning this? I'm hoping someone can prove me wrong, so fire away.
Good luck with everything.
-f4
This may not be the case, so don't let it discourage anyone from trying it. It would definitely allow the use of many displays that were previously unusable for this purpose, and I am very much in favor of that. Does anyone have any ideas concerning this? I'm hoping someone can prove me wrong, so fire away.
Good luck with everything.
-f4
fender4,
You gave the answer yourself!
1. Because of the little distance between LCD-panel and fresnel-mirror you will have a setoff for all reflected beams that don't pass exactly the middle of th panel.Make a drawing and consider the lightpath also for the beams at the corners of the panel.
Remember:angle of incidence = angle of output.
2. Consider the loss of brightness through the panel. If the panel let 10% of light transmit the way down it does the same when the light comes up again.
3. There would be a heat trap problem between mirror and panel.
My opinion: forget it!
xblocker
You gave the answer yourself!
1. Because of the little distance between LCD-panel and fresnel-mirror you will have a setoff for all reflected beams that don't pass exactly the middle of th panel.Make a drawing and consider the lightpath also for the beams at the corners of the panel.
Remember:angle of incidence = angle of output.
2. Consider the loss of brightness through the panel. If the panel let 10% of light transmit the way down it does the same when the light comes up again.
3. There would be a heat trap problem between mirror and panel.
My opinion: forget it!
xblocker
Thanks, xblocker. I had a feeling that would be the case. I didn't think about the heat trapping effect...good call.
Muzzman,
Thanks for the input. The Sharp panel I had was advertised as a TFT, but it was an odd arrangement of pins surrounding the active area of the panel. I'm really not sure what was going on with that. Luckily I was able to return it for a refund. I will look into the PS1 LCD...that resolution should be fine for me as I will mostly be using it for movies on a roughly 60" screen.
-f4
Muzzman,
Thanks for the input. The Sharp panel I had was advertised as a TFT, but it was an odd arrangement of pins surrounding the active area of the panel. I'm really not sure what was going on with that. Luckily I was able to return it for a refund. I will look into the PS1 LCD...that resolution should be fine for me as I will mostly be using it for movies on a roughly 60" screen.
-f4
Got my Elmo HP-A305 8K Lumens
And am not sure if I wasted $150...
The metal halide OHPs are quite the complicated beast. Two fans and it roars when in operation. It's got a full fledged power supply, with ICs and chokes and big heat sinks. Daughter cards with more ICs. This giant flyback transformer that hooks to the bulb. A far cry from the Duke 4003 which had a few switches, a couple diodes and a resistor.
It's so bright inside the thing that you cant even look through the big fan, you burn your eyes; not kidding.
The @#%^&()^ arm that holds the overhead mirror and lens is really crappy; I had to like bend it to get the lens at a right angle to the stage. This, from supposedly a multi K$ machine...The Duke, in contrast, has an adjustment to set this.
The light is super bright in high intensity mode, but not perfectly uniform. We'll see if that gets better after a good cleaning.
Aside from this, I did have a bit of luck. The place I bought it from just happened to have a broken Nview Z350. I had em send it along for an extra $40. Only 2/3 of the screen had active pixels when I turned it on. So, I opened it up, poked and prodded and was lucky to see some changes in the LCD when I pushed on this circuit card off to one edge.
I was even luckier when I removed the LCD, took the EMI shield off and noticed that a couple of flex-print conductors that looked like it was connected to a driver chip had desoldered from this PCB. (I could just see the flex print move when touched. The driver chips must get really hot) So I reflow soldered each connection back down, cleaning up my solder bridges with the chem-wick, retouching 15 or so connections. So, soldering these kinds of tiny connections can be done. It's just somehow easier to do on a $40 panel than a $300 panel, you're not quite so nervous.
Even luckier was I when I put this back into the panel, hooked it all up, powered on and the entire LCD now shows an image! I reversed the panel fan, so it blows in the same direction as my other unit. I think this was a problem on these panels, because the fan on my other one blows out through the air filter element, which the manual says to keep clean, so dust doesnt get on the inside panel glass. That's not logical, so they mustve reversed it because the panels were all burning up and maybe that fixed it.
The thickness of this LCD element was appx 1/8". I'd think the newer ones would be even thinner, but, who knows?
Anyway, I'm writing this on a 50" screen, using my new Elmo projector and the repaired Z350.
I cant convince myself that the reflective mode OHP will definitely work, using an LCD panel with the reflector lens mounted right on the back. I cant even crank through how it would work with a transparency! The only part I understand is without any interferance, the fresnel reflector collumnates the light so its equal brightness across the stage area, with the direction being straight up.
And am not sure if I wasted $150...
The metal halide OHPs are quite the complicated beast. Two fans and it roars when in operation. It's got a full fledged power supply, with ICs and chokes and big heat sinks. Daughter cards with more ICs. This giant flyback transformer that hooks to the bulb. A far cry from the Duke 4003 which had a few switches, a couple diodes and a resistor.
It's so bright inside the thing that you cant even look through the big fan, you burn your eyes; not kidding.
The @#%^&()^ arm that holds the overhead mirror and lens is really crappy; I had to like bend it to get the lens at a right angle to the stage. This, from supposedly a multi K$ machine...The Duke, in contrast, has an adjustment to set this.
The light is super bright in high intensity mode, but not perfectly uniform. We'll see if that gets better after a good cleaning.
Aside from this, I did have a bit of luck. The place I bought it from just happened to have a broken Nview Z350. I had em send it along for an extra $40. Only 2/3 of the screen had active pixels when I turned it on. So, I opened it up, poked and prodded and was lucky to see some changes in the LCD when I pushed on this circuit card off to one edge.
I was even luckier when I removed the LCD, took the EMI shield off and noticed that a couple of flex-print conductors that looked like it was connected to a driver chip had desoldered from this PCB. (I could just see the flex print move when touched. The driver chips must get really hot) So I reflow soldered each connection back down, cleaning up my solder bridges with the chem-wick, retouching 15 or so connections. So, soldering these kinds of tiny connections can be done. It's just somehow easier to do on a $40 panel than a $300 panel, you're not quite so nervous.
Even luckier was I when I put this back into the panel, hooked it all up, powered on and the entire LCD now shows an image! I reversed the panel fan, so it blows in the same direction as my other unit. I think this was a problem on these panels, because the fan on my other one blows out through the air filter element, which the manual says to keep clean, so dust doesnt get on the inside panel glass. That's not logical, so they mustve reversed it because the panels were all burning up and maybe that fixed it.
The thickness of this LCD element was appx 1/8". I'd think the newer ones would be even thinner, but, who knows?
Anyway, I'm writing this on a 50" screen, using my new Elmo projector and the repaired Z350.
I cant convince myself that the reflective mode OHP will definitely work, using an LCD panel with the reflector lens mounted right on the back. I cant even crank through how it would work with a transparency! The only part I understand is without any interferance, the fresnel reflector collumnates the light so its equal brightness across the stage area, with the direction being straight up.
Attachments
Nice pic!
Hey.
jjasniew -
Nice screenshot!! So did you just get a spare panel the same as your existing one? The color looks a little off, but the contrast looks pretty good! I _highly_ recommend a capture card+dscaler to send TV/composite/s-video to your projector. I've been experimenting with it for a few days and it can make TV look better than I ever thought it could. ONly problem is I can't get stereo sound from my TV tuner.
I almost bought a projector from Ebay last night. Don't banish me from the DIY brotherhood!! I'm sure the reason that a lot of us are doing this project is because we just want a projector! This was an 800x600 500 lumen 250:1 contrast ratio projector on ebay- "Buy it now for US$250". Someone got to it before I caved. Mabye it's better that way. Going to either get my $$ back or a new Rad5 hopefully in a few days, don't know where I'll go from there. I'm just a rambling man....
Hey.
jjasniew -
Nice screenshot!! So did you just get a spare panel the same as your existing one? The color looks a little off, but the contrast looks pretty good! I _highly_ recommend a capture card+dscaler to send TV/composite/s-video to your projector. I've been experimenting with it for a few days and it can make TV look better than I ever thought it could. ONly problem is I can't get stereo sound from my TV tuner.
I almost bought a projector from Ebay last night. Don't banish me from the DIY brotherhood!!
I'm sure the reason that a lot of us are doing this project is because we just want a projector! This was an 800x600 500 lumen 250:1 contrast ratio projector on ebay- "Buy it now for US$250". Someone got to it before I caved. Mabye it's better that way. Going to either get my $$ back or a new Rad5 hopefully in a few days, don't know where I'll go from there. I'm just a rambling man....If you wanna see some easter eggs look here:
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=1338117492
and here:
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=1337877173
I never saw such an offer..! (Couldn't resist to show it here)
xblocker
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=1338117492
and here:
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=1337877173
I never saw such an offer..! (Couldn't resist to show it here)
xblocker
- Status
- Not open for further replies.