Alright, I have been reading through the forums here and on a couple of other sites for a while now and have decided I want to take a stab at building my own projector. But I have some questions that I am hoping the gurus here can help me answer.
First off I want something that is capable of providing at least 720p resolution. Currently I have this monitor:
17"
0.264mm
96.2 @ native resolution
250 cd/m2
500:1
160° Vert., 160° Hor.
(85U/75D/80L/80R)(CR>5)
Rapid Response (12ms)
More than 16 million
31.5-81 kHz (Analog)
31.5-69 kHz (Digital)
56-75 Hz
ANALOG 0.7 Vp-p / 75 Ohms
Separate sync: TTL Level
(Positive/Negative)
Composite sync: TTL Level
(Positive/Negative)
Composite sync on green:
(0.3 Vp-p negative 0.7 Vp-p positive)
DVI-D and VGA 15 pin D-sub
ANALOG/ DIGITAL
720 x 400 @ 70 Hz
640 x 480 @ 60-75 Hz
800 x 600 @ 56-75 Hz
832 x 624 @ 75 Hz
1024 x 768 @ 60-75 Hz
1152 x 870 @ 75 Hz
1280 x 1024 @ 60-75 Hz
1280 x 1024 @ 60 Hz
Thin-frame (bezel), No Touch Auto
Adjust, NaViSet software, USB 2.0, sRGB,
AccuColor color control, digital smoothing,
digital controls, Plug and Play (VESA DDC
1/2B), VESA DPMS power management, OSM
user controls, ISO 13406-2 Class II, vacation
switch, height-adjustable stand
AC 100-120V/AC 220-240V
48W
<2W
14.4 x 14.3-18.6 x 7.8 in/
367 x 362.5-472.5 x 198mm
14.4 x 12.5 x 2.3 in/
367 x 317 x 59.5mm
13.4 lbs/6.1 kg
9.5 lbs/4.3 kg
100 x 100mm
I believe that this should be capable of that correct?
Is 500:1 contract decent? How does the contract ratio of a monitor compare to say a plasma TV with a rating of 4000:1?
Can someone explain cd/m2 to me? Is this relevant to my project?
I realize that this is large panel for this type of project and may require some additional work. What types of things do I need to be aware of with a 17" LCD?
It seems that the holy grail of projectors is brightness. I am surprised that I have not seen any plans calling for the use of multiple lights. Why is this?
I have also seen discussion of both MH bulbs and UHP bulbs, any recommendations? Or is this comparing apples and oranges?
Lastly, while not directly related to building the projector at some point I am going to want to plug things into it so I can watch them. How do you get YPrPb and other such connections to your projectors?
Well that's a good start. I am sure I will have more as this progresses.
Thanks,
Matt
First off I want something that is capable of providing at least 720p resolution. Currently I have this monitor:
17"
0.264mm
96.2 @ native resolution
250 cd/m2
500:1
160° Vert., 160° Hor.
(85U/75D/80L/80R)(CR>5)
Rapid Response (12ms)
More than 16 million
31.5-81 kHz (Analog)
31.5-69 kHz (Digital)
56-75 Hz
ANALOG 0.7 Vp-p / 75 Ohms
Separate sync: TTL Level
(Positive/Negative)
Composite sync: TTL Level
(Positive/Negative)
Composite sync on green:
(0.3 Vp-p negative 0.7 Vp-p positive)
DVI-D and VGA 15 pin D-sub
ANALOG/ DIGITAL
720 x 400 @ 70 Hz
640 x 480 @ 60-75 Hz
800 x 600 @ 56-75 Hz
832 x 624 @ 75 Hz
1024 x 768 @ 60-75 Hz
1152 x 870 @ 75 Hz
1280 x 1024 @ 60-75 Hz
1280 x 1024 @ 60 Hz
Thin-frame (bezel), No Touch Auto
Adjust, NaViSet software, USB 2.0, sRGB,
AccuColor color control, digital smoothing,
digital controls, Plug and Play (VESA DDC
1/2B), VESA DPMS power management, OSM
user controls, ISO 13406-2 Class II, vacation
switch, height-adjustable stand
AC 100-120V/AC 220-240V
48W
<2W
14.4 x 14.3-18.6 x 7.8 in/
367 x 362.5-472.5 x 198mm
14.4 x 12.5 x 2.3 in/
367 x 317 x 59.5mm
13.4 lbs/6.1 kg
9.5 lbs/4.3 kg
100 x 100mm
I believe that this should be capable of that correct?
Is 500:1 contract decent? How does the contract ratio of a monitor compare to say a plasma TV with a rating of 4000:1?
Can someone explain cd/m2 to me? Is this relevant to my project?
I realize that this is large panel for this type of project and may require some additional work. What types of things do I need to be aware of with a 17" LCD?
It seems that the holy grail of projectors is brightness. I am surprised that I have not seen any plans calling for the use of multiple lights. Why is this?
I have also seen discussion of both MH bulbs and UHP bulbs, any recommendations? Or is this comparing apples and oranges?
Lastly, while not directly related to building the projector at some point I am going to want to plug things into it so I can watch them. How do you get YPrPb and other such connections to your projectors?
Well that's a good start. I am sure I will have more as this progresses.
Thanks,
Matt
I'll answer some of your questions...Dazofthndr said:
first,
720p means 60hz(60fps) @ 720x1280 res. wich means 921 600 pixels.
that 17'' moniror can display 1280x1024 res. (=1310720 pixels) @ 60Hz(60fps)
...so that monitor can actually surpass 720p quality.
second,
500:1 contrast ratio is very decent, if you have a decent bulb of more than 30 000 lumens, you'll be able to see great even with lights on (if not abusive)
third,
17'' projectors do take special mesures, you'll need a slighly more powerfull light, but that's no big problem really, you'll also need bigger fresnel lenses (used to concentrate light on the lcd and after into the projection lens, they are usually made out of plastic and can be found at sites like www.lumenlab.com) The lens required for 17'' LCDs are more expensive if I can remember correctly...
remember that the box containing your lcd will have to be bigger too, somewhat not practical.
I'd stick to 15'' for a first project.
fourth,
multiple lights require more Watts and result in more heat, the ultimate goal here is to have the most light (lumens) with the less power (Watts), search for 300-400watts bulbs, again, www.lumenlab.com has some killer light kits, but they are quite expensive.
fifth,
MH stands for metal halide, the 'U' is, if I remember correctly, only there to tell you that you can stand the bulb in an horizontal or vertical way.
lastly,
to connect most of your video signals to your LCD you'll propably prefer passing the data with a PCI video card in your PC. The only prob here is that it brings up lag (delay), not tolerable for gaming. You'll then need to look for some RCA/Component to VGA adaptors, you can look up www.liksang.com.
Peace, have fun planning your DIYP!
keep us updated.
..."Candelas per meter squared, or cd/m², is a unit of measure that used to be called "nits." Broken down, candela, abbreviated as cd, is a term that originated in the days when candles were used in theaters. For our purposes, candelas per meter squared measures the light properties radiating from a one-meter-square surface, providing a technical frame of reference for the performance of a display's black level, peak brightness, grayscale and gamma readings."...
http://www.presentations.com/presentations/technology/article_display.jsp?vnu_content_id=1000543352
cd/m2 is not relavent to DIY projectors because we are replacing the backlight.
MH vs UHP is not apples to oranges but more like old technology to new technology. I believe that UHP stands for Ultra high performance or I have also heard it called Ultra high pressure. Either way they are both very similar. The key is finding the one with the spec's for your setup.
Contrast is very subjective. It depends on you and your acceptable black level. The general rule is the more the better. 500:1 is middle of the road for LCD monitors
I think one of the biggest problems with 17" lcd's is trying to find a projection lens that can capture all of the usable light, all of the viewable image and still be able to focus the entire image. Last I heard people were having sucuss with the lens from an opaque projector.
Zaner21
http://www.presentations.com/presentations/technology/article_display.jsp?vnu_content_id=1000543352
cd/m2 is not relavent to DIY projectors because we are replacing the backlight.
MH vs UHP is not apples to oranges but more like old technology to new technology. I believe that UHP stands for Ultra high performance or I have also heard it called Ultra high pressure. Either way they are both very similar. The key is finding the one with the spec's for your setup.
Contrast is very subjective. It depends on you and your acceptable black level. The general rule is the more the better. 500:1 is middle of the road for LCD monitors
I think one of the biggest problems with 17" lcd's is trying to find a projection lens that can capture all of the usable light, all of the viewable image and still be able to focus the entire image. Last I heard people were having sucuss with the lens from an opaque projector.
Zaner21
How do I figure out what size lense will work for focusing the image at a given distance? Or is it simply trial and error?
Are there benefits to a folded light path other than space saving?
Does anyone have plans or drawings of the projectors they have built using a 17" LCD?
Should I look for a monitor with more than a 500:1 contrast ratio?
Does anyone here have experience with either the Vdigi or Viewsonic N6, or ever better both?
Are there benefits to a folded light path other than space saving?
Does anyone have plans or drawings of the projectors they have built using a 17" LCD?
Should I look for a monitor with more than a 500:1 contrast ratio?
Does anyone here have experience with either the Vdigi or Viewsonic N6, or ever better both?
"Are there benefits to a folded light path other than space saving?"
Yes, if the light path is folded via the use of an odd # of mirrors after the LCD then the image will not need to be reversed. Straight through designs require that either the LCD panel be flipped, or the signal be reversed prior to feeding it to the LCD.
"Should I look for a monitor with more than a 500:1 contrast ratio?"
The higher the contrast the better obviously, but I think the general consensus is anything 300:1 or up will suffice.
Yes, if the light path is folded via the use of an odd # of mirrors after the LCD then the image will not need to be reversed. Straight through designs require that either the LCD panel be flipped, or the signal be reversed prior to feeding it to the LCD.
"Should I look for a monitor with more than a 500:1 contrast ratio?"
The higher the contrast the better obviously, but I think the general consensus is anything 300:1 or up will suffice.
You bring up a good point about why not more bulbs? Well, I was just thinking it might work. Picture instead of using one 400W bulb, use four 100W bulbs. Instead of using one back fresnel (the one before the LCD), use four back fresnels that correspond to each bulb.
The light might be more evenly distributed. Granted you'll have 4 light circles instead of one, but the light fall off might be small enough that it isn't noticable.
The reason you normally want to use one bulb is because the back fresnel lens takes light from a point (the arc of the bulb) and magnifies it to be distributed evenly on the LCD. There is only one focal point on the fresnel, so multiple bulbs wouldn't work. But if you used 4 fresnels..... Hmmm..... The only other problem I see is that you might need 4 power supplies for the bulbs; unless there is a way to chain four 100W MH bulbs into a 400W power supply... HMmmmmm.....
The light might be more evenly distributed. Granted you'll have 4 light circles instead of one, but the light fall off might be small enough that it isn't noticable.
The reason you normally want to use one bulb is because the back fresnel lens takes light from a point (the arc of the bulb) and magnifies it to be distributed evenly on the LCD. There is only one focal point on the fresnel, so multiple bulbs wouldn't work. But if you used 4 fresnels..... Hmmm..... The only other problem I see is that you might need 4 power supplies for the bulbs; unless there is a way to chain four 100W MH bulbs into a 400W power supply... HMmmmmm.....
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