modern commercial projectors use a complicated system of color filters and lenses to take an image from three LCDs and compile it into one image to go through one lens. The LCDs themselves range in size from .9" diagonal to 3.2" diagonal in older projectors. They have resolutions of VGA (640x480) up to SXGA (1280X1024) but use proprietary electronics that are built into the projector and are themselves very expensive. Occasionally you will see some surplus parts up on ebay, but they are usually useless by themselves.
Some older commercial projectors use a single full color LCD design. This is the design that most of the DIY projects are modeled after (see Ace's project or Brainchild's website lumenlab.com for more info on that). Because we do not have the vast monetary and technological resources that major corporations have at their disposal, we cannot create the complicated system that will allow for us to take the light from a lamp, send it in three different pathways through three color filters and three LCDs, then reassemble it through a prism and a projection lens.
If you feel so inclined and have the time and money, all the more power to you. I'd love to see someone try it. I personally think it is currently beyond the scope of DIY because of the difficulty of locating inexpensive small monochrome LCDs and the complexity of the optics in commercial projectors. If you search around the forum you might be able to find some pictures of gutted commercial projectors, I seem to remember somebody posting some a while back. Usually you can't really see much of the optics, it generally looks like a mess of PCBs and wire.
We are not trying to reinvent the wheel. We are simply returning to the wheel after deciding that an antigravity device was simply not a feasible thing to construct in our backyard (or some other similar metaphor).
Some older commercial projectors use a single full color LCD design. This is the design that most of the DIY projects are modeled after (see Ace's project or Brainchild's website lumenlab.com for more info on that). Because we do not have the vast monetary and technological resources that major corporations have at their disposal, we cannot create the complicated system that will allow for us to take the light from a lamp, send it in three different pathways through three color filters and three LCDs, then reassemble it through a prism and a projection lens.
If you feel so inclined and have the time and money, all the more power to you. I'd love to see someone try it. I personally think it is currently beyond the scope of DIY because of the difficulty of locating inexpensive small monochrome LCDs and the complexity of the optics in commercial projectors. If you search around the forum you might be able to find some pictures of gutted commercial projectors, I seem to remember somebody posting some a while back. Usually you can't really see much of the optics, it generally looks like a mess of PCBs and wire.
We are not trying to reinvent the wheel. We are simply returning to the wheel after deciding that an antigravity device was simply not a feasible thing to construct in our backyard (or some other similar metaphor).
Thats crap, ofcourse we can, but look at the cost! the optics are cheap, its the panels that are exspensive, and i dont see it feasable to make a 3lcd projector with 3x 6inch panels. Thats why im not overly fissed with 3lcd units, however my next is a 2 panel projector but for stereoscopic 3d use, (toatally diff thing)
Trev
I totally agree ace,
vassarguy, I am spending a lot of time now learning about projection, and a lot of seems so simple, I could easily make a 3LCD projector, but the cost would be too high. These complicated systems you talk about is simply laying out the dichroic mirrors (to split colours), prisms and other parts which we already use.
vassarguy, I am spending a lot of time now learning about projection, and a lot of seems so simple, I could easily make a 3LCD projector, but the cost would be too high. These complicated systems you talk about is simply laying out the dichroic mirrors (to split colours), prisms and other parts which we already use.
Sorry to offend, I guess I overstepped the bounds of my own knowledge a bit. Out of curiosity, Ace, how much would a suitable optical system cost?
Bobharry, I was trying to communicate to johnjohn2 that at this stage the "state of the art" of DIY is still working on perfecting the single panel LCD projector, and that for reasons of money and the availability of certain parts (where would you get three perfectly matched monochrome LCDs?) projectors with multiple LCDS aren't feasible at this point
Bobharry, I was trying to communicate to johnjohn2 that at this stage the "state of the art" of DIY is still working on perfecting the single panel LCD projector, and that for reasons of money and the availability of certain parts (where would you get three perfectly matched monochrome LCDs?) projectors with multiple LCDS aren't feasible at this point
That depends, if you bought new or secondhand and where from, also quality would also be the thing.
I could obtain a whole 3 lcd projectors optics for about $200 and up, ofcourse thats if you can find the colour filters cheap. That would also be new optics but obviously not the best, if you wanted to go the next level up, try about $500, after that if you want the best, try $2k and up.
Regarding the lcds being perfectly aligned, no lcd is perfectly aligned, sure the polarisers and pixels are (within reason), but forget about the outer screen size being perfect, even pro projectors dont have perfect lcds hence ajustments.
If you realy want my thoughts on a lcd, well even though they project nice they are crap for projection, this is namly due to the eficientcy level, and typically why dlp was invented, however this isnt talking about lcos tech ofcourse. Lcos will out do any dlp chip by far as in reso and reflectance, but look at the darn price! lol
There are new techs coming out at the end of this year and next year, they will be afordable and they wont be using a lamp, it will be interesting to see what it is.
Trev
Wow, thanks for the great responses. So from what I understand, tiny lcd's with high resolutions do exist. They're just too expensive right now. Other than that are the basics the same as to what's being done on the forum? or do the commercial projectors using other tricks, other than the 3 lcd setup? By the way, are the 3 lcd systems used in order to get more light through the system, or just better color?
Yeah the basics are the same as what we do here, but they have a lot more parts available to them, but they do use much brighter lamps, hence the shorter life, theres probably other tricks they use as well but I'm not sure. The 3 lcd system is used to make the picture brighter, higher contrast and better colour, one advantage with it is that because they are monochome, the pixels don't have sub-pixels of different colours, so when all three are merged, the pixels are already mixed instead of relying on your eye to blur the colours together, making the colour better no matter how close you are to the screen.
Commercial projectors dont use brighter lamps. Just smaller arc's... resulting in the shorter lifespans. The 3 black and white LCD's are used to get a higher contrast and richer colors. By using 3 B&W high res panels, each focusing on one color they can achieve millions upon millions of colors. Where a single panel unit relies solely on the panels specs and can get wasted if you put too much light through it to get a brighter picture.
Other then small high res panels and color filters the only other thing commercial projectors use that we dont are prisms. Because of the small panels they can get true 1:1 imaging keeping all of the optics the same size or larger then what they project.
JCB
www.diybuildergroup.com
Other then small high res panels and color filters the only other thing commercial projectors use that we dont are prisms. Because of the small panels they can get true 1:1 imaging keeping all of the optics the same size or larger then what they project.
JCB
www.diybuildergroup.com
Dont forget the DLP chips some projectors use too. these consist of a large silicone chip with millions of tiny micromachined mirrors on thw surface which can be angled to the light source so that they are on or off, allowing for very good image reproduction without a lot of the problems you get from the pixels being visible on some LCD type projectors.
Texas Instuments DLP.
Texas Instuments DLP.
You might wana take a rain cheack on that one buddy, ive read on a few sites that alot of 2k lumen projectors use 90k lumen bulbs,( typical of 300w+). If i find one of the site's i read, ill post it up.
Bob, small arc lamps dont last aslong as they are under a very high presure, the arc also is very small and has less time for the tungsten to build up in the arc tube resulting in a dead bulb. Only better gasses can fix this and not running the lamp at full power, or at an over driven state.
If you go to www.analog.com and take a look at the AD8382 data sheet, for instance, you can get an idea of some of the custom drive electronics that have been developed for LCD's. This path is definately not DIY.
Q28: What is the difference between metal halide and UHP lamp technologies?
A28: A UHP (Ultra High Performance) lamp is a proprietary design of Metal Halide lamp manufactured by Philips that requires lower wattage for equivalent brightness, resulting in:
1) a smaller and lighter projector, because the power supply is smaller and lighter.
2) a cooler running, quieter, and less expensive-to-operate projector because of the lower wattage
3) a longer lamp life, because the stresses on the lamp (wattage, temperature change) are reduced.
4) UHP lamps last approximately 4000 hours whereas metal halide lamps last approximately 1000 hours.
Dont be fooled guys they are not the same lamps with the same brightness, thats just a hint, there are also EUHP bulbs, i will find the exact specs of a projector bulb in a site that i saw some time ago, asoon as i have time!
A28: A UHP (Ultra High Performance) lamp is a proprietary design of Metal Halide lamp manufactured by Philips that requires lower wattage for equivalent brightness, resulting in:
1) a smaller and lighter projector, because the power supply is smaller and lighter.
2) a cooler running, quieter, and less expensive-to-operate projector because of the lower wattage
3) a longer lamp life, because the stresses on the lamp (wattage, temperature change) are reduced.
4) UHP lamps last approximately 4000 hours whereas metal halide lamps last approximately 1000 hours.
Dont be fooled guys they are not the same lamps with the same brightness, thats just a hint, there are also EUHP bulbs, i will find the exact specs of a projector bulb in a site that i saw some time ago, asoon as i have time!
Commercial projectors use 3 Polysilicon tft panels and most also use microlenses which can let through twice as much light as normal tft-panels. Polysilicon tft panels have much better preformance than normal tft, but they can only be made about 1" large, this is why the commercialprojector panel is so small. Small panels need a small reflector, a small reflector needs a small lamp and a small arc-size.
Today the name of a small arc lamp is UHP or UHM, older projectors use "true short arc xenon". A UHP-lamp is not brighter than a HQI-lamp, the HQI-lamp give more lumens than the same wattages UHP-lamp. It´s the small arc-size that make the UHP-lamp to a perfect pointsource and with a perfect point source you can use 100% of the light and direct that to the small lcd-panels.
If the UHP-lamps was so much brighter than HQI-lamps why do you think they are not used more than in projectors ?
The last Single panels lcd projectors was made about 1996-1998 and there is a reason why they don´t do these any more. Most Single panels projectors have a 350W MH lamp and give 150-200 ansilumens and this is what you can expect of a DIY-projector with the same wattages lamp.
Today the name of a small arc lamp is UHP or UHM, older projectors use "true short arc xenon". A UHP-lamp is not brighter than a HQI-lamp, the HQI-lamp give more lumens than the same wattages UHP-lamp. It´s the small arc-size that make the UHP-lamp to a perfect pointsource and with a perfect point source you can use 100% of the light and direct that to the small lcd-panels.
If the UHP-lamps was so much brighter than HQI-lamps why do you think they are not used more than in projectors ?
The last Single panels lcd projectors was made about 1996-1998 and there is a reason why they don´t do these any more. Most Single panels projectors have a 350W MH lamp and give 150-200 ansilumens and this is what you can expect of a DIY-projector with the same wattages lamp.
I'll say it again... commercial projectors dont use brighter lamps... just smaller arcs. Are there commercial units with brighter lamps then what we use?... SURE. But that isnt the normal and isnt found in the majority. Do-It-Yourselfers have used 1000watt lamps in the past with lumen output that far exceeds any typical commercial projector bulb. Hell, the 400 watter I'm using has the average lumen output higher then most high quality commercial unit bulbs.
From my testing commercial units use small arcs because they use 1" LCD's! For a 1" LCD with optics roughly the same size you need a pretty dame small point source! 15" LCD's DONT need such a small arc.
You come by my place and tell me my 400 Watt MH with NEC V50LCD is only pushing 150-200 ansi lumens! Your nuts! I've seen my DIY unit side by side with a $5k NEC XGA 2500 ansi lumen projector recently. Is my unit brighter? Of course not. But the $5,000 NEC isnt 4 times brighter! Hell it isnt even twice as bright... which means I'm putting out at LEAST 1100 ansi lumens. Easy. The one thing I did notice was a big difference in color and screen door. The NEC had far richer colors and screen door was less noticable at close viewing. The DIY Unit does have good coloring... but to get it even close to the NEC it takes a computer and A LOT of tweaking the settings.
JCB
www.diybuildergroup.com
bigparsnip said:
TI has spent a lot of money in dlp. They originally thought that the biggest market for dlp is cinema projectors: essentially "films" in the future will be downloaded to cinemas and DLP'd onto the screen, allowing studios great control over cinema revenues.
They were surprised at how strong dlps are being used on home theater / hd tv now.
Not sure if LCOS will eventually take over and I am not even sure if DLP is the future (for the next 3-5 years) for home use (dlps suffer from visible pivots, which TI claims to have resolved). LCOS has the potential of being a lot more mass-production friendly than DLP. But you got FED and LCD out there (and OLED too) so who knows.
Thats acutaly only partly right, the 1 inch lcd bit that is, they actually use smaller arcs so they can use smaller reflectors or vice versa, a reflector can only match a certain arc size no matter what type it is or what the optics are that the light is going through, that is a fact, i sujest you do abit more reading on the matter, this has even been worked out on this site.
eherm
A UHP (Ultra High Performance) lamp is a proprietary design of Metal Halide lamp manufactured by Philips that requires lower wattage for equivalent brightness
We use standard industrial metal halides, they dont, they use higher eficientcy metal halide bulbs especially made! for a higher lumen per watt spec, they also use the same wattage as we do and thats where the confusion is, and yess with a smaller arc to optimise the control of light with a smaller reflector. Do some reading around, the info is out there and its not hard to find.
Ya and with the comercial unit being brighter lol.
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