Dear Diy-crew,
I've been playing with this idea for a while now and now I think I should share.
Everyone here wants to build a lcd projector but small hi-rez inexpensive lcds are hard to come by and 15" are hard to work with so my idea revolves around the 5" lcds from partsexpress (set to display in "BLACK - WHITE". However, my idea calls for 3 of them (represented in blue). Then 3 light sources, of course one is green one blue and one red (run through colored filters. These can be regular (hi wattage) HI bulbs (100-150W) and three small index card size fresnels (for obvious reasons).
The only problem I see here is the prizm. It has to be at least the same size as the lcds. A prizm is nothing more than 4 triagle pieces of glass put together (represented as a box with an X in it). I imagine it could be found or ordered from a glass shop??
If all three lcd & lamp fixtures are built exactly the same i would imagine it would be easy to align. And with 3 lcds you get 3 times the resolution. This is the same way commercial projectors work.
ap0
I've been playing with this idea for a while now and now I think I should share.
Everyone here wants to build a lcd projector but small hi-rez inexpensive lcds are hard to come by and 15" are hard to work with so my idea revolves around the 5" lcds from partsexpress (set to display in "BLACK - WHITE". However, my idea calls for 3 of them (represented in blue). Then 3 light sources, of course one is green one blue and one red (run through colored filters. These can be regular (hi wattage) HI bulbs (100-150W) and three small index card size fresnels (for obvious reasons).
The only problem I see here is the prizm. It has to be at least the same size as the lcds. A prizm is nothing more than 4 triagle pieces of glass put together (represented as a box with an X in it). I imagine it could be found or ordered from a glass shop??
If all three lcd & lamp fixtures are built exactly the same i would imagine it would be easy to align. And with 3 lcds you get 3 times the resolution. This is the same way commercial projectors work.
ap0
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Wow, that is cool! I want to try that!
I've been wanting to build an LCD projector powered by high-intensity LEDs (cost, yeah, I know... I don't want to replace bulbs or worry about the thing getting kicked; it's worth that much to me) because LEDs will give INFINITELY better color than filtered metal halides....
so... the hard part is the prisms, eh? Let's see if we can find something serviceable for this.... I want to try it. 🙂
I've been wanting to build an LCD projector powered by high-intensity LEDs (cost, yeah, I know... I don't want to replace bulbs or worry about the thing getting kicked; it's worth that much to me) because LEDs will give INFINITELY better color than filtered metal halides....
so... the hard part is the prisms, eh? Let's see if we can find something serviceable for this.... I want to try it. 🙂
The prisms as shown in your diagram won't work, but you are getting closer to a good design.
Here's a few of the points of inefficiency:
Filtering light turns light into heat. Best case, a white light going through a red filter will waste the green and blue light.
So, overall, you will have 2/3 of your light wasted, right at the source. (All 3 source will each waste 2/3 of their light).
Passing red light through a color LCD set to B/W is going to waste another 2/3 of your light, because only 1/3 of the pixels will pass the red light through. The blue and green pixels will not pass your red light. (All 3 LCD's will each waste 2/3 of their light).
If you could get true monochrome LCD panels (that don't have any colored filters) and feed them just one signal (like one LCD gets just the 'red' signal), then you could add them up like this.
If you could remove the color filters from a color LCD and send it just one color signal to all three inputs, that would work as well.
Look at your design and try to replace filters with dichroic mirrors (or a prism, even) to seperate the light into the desired colors, rather than filtering.
You can also use these mirrors to re-assemble the light from the 3 LCD's prior to going out to the screen, via the objective lens.
Here's a few of the points of inefficiency:
Filtering light turns light into heat. Best case, a white light going through a red filter will waste the green and blue light.
So, overall, you will have 2/3 of your light wasted, right at the source. (All 3 source will each waste 2/3 of their light).
Passing red light through a color LCD set to B/W is going to waste another 2/3 of your light, because only 1/3 of the pixels will pass the red light through. The blue and green pixels will not pass your red light. (All 3 LCD's will each waste 2/3 of their light).
If you could get true monochrome LCD panels (that don't have any colored filters) and feed them just one signal (like one LCD gets just the 'red' signal), then you could add them up like this.
If you could remove the color filters from a color LCD and send it just one color signal to all three inputs, that would work as well.
Look at your design and try to replace filters with dichroic mirrors (or a prism, even) to seperate the light into the desired colors, rather than filtering.
You can also use these mirrors to re-assemble the light from the 3 LCD's prior to going out to the screen, via the objective lens.
ap0the0sis said:
all three lcds will get the same video signal. overlap them would increase the resolution. I cannot see how you can get 3 times the resolution without invest money on some special board.
And reflector will give you more trouble than the trouble from any other designs combined.
ap0the0sis said:
i dont quite follow how you will get a higher resolution if your gonna line up the lcd's
wont it just stack the pixels on top of each other giving the same res?
If your going to try the 3 lcd approach you might as well just copy one of the commercial projectors on the market. The designs are exactly what your looking for.
Using 3 light sources will be a waste and create more problems then solutions.
And this approach will also drive the price up to the point where I dont think you'll be able to justify the resolution with the cost.
Using 3 light sources will be a waste and create more problems then solutions.
And this approach will also drive the price up to the point where I dont think you'll be able to justify the resolution with the cost.
No, you won't get 3 times the resolution, because you will be stacking 3 320x200 images (thats the rez on those partexpress panels, right?), ontop on eachother.
What you will do though is totally eliminate screen door, so it will look better than a regular 320x200 projector
What you will do though is totally eliminate screen door, so it will look better than a regular 320x200 projector
Well I own a commercial lcd projector, Epson 5500C. Im not in the process of building a diy projector yet and if I do it'll be for my 10yr old bro. This idea was for you guys to play with and see if something can come from it.
My idea on 3 times the resolution is true because in commercial projectors (like mine) each lcd panel is 800x600 so that means that each panel gives you a resolution of 480,000 pixels. Now multiply that by 3 and you get 1,440,00. That is the resolution of my projector. Now I believe that these numbers are right because you have to remember that you dont have 3 colors per lcd anymore. Now its one color per lcd so your using the 480,000 for red, 480,000 for blue and 480,000 for green. of course the lcd panels in parts express have less resolution but still adds up the same. You get the idea.
neededandwanted, I dont know where you came from but you seem to know what you're talking about. I understand that by using 3 lights it would waste power/heat but i was thinking about it to simplify things a bit.
The prism in my figure is exactly like the one in my commercial projector. thats why i know it works.
ap0
My idea on 3 times the resolution is true because in commercial projectors (like mine) each lcd panel is 800x600 so that means that each panel gives you a resolution of 480,000 pixels. Now multiply that by 3 and you get 1,440,00. That is the resolution of my projector. Now I believe that these numbers are right because you have to remember that you dont have 3 colors per lcd anymore. Now its one color per lcd so your using the 480,000 for red, 480,000 for blue and 480,000 for green. of course the lcd panels in parts express have less resolution but still adds up the same. You get the idea.
neededandwanted, I dont know where you came from but you seem to know what you're talking about. I understand that by using 3 lights it would waste power/heat but i was thinking about it to simplify things a bit.
The prism in my figure is exactly like the one in my commercial projector. thats why i know it works.
ap0
ap0the0sis said:
hey man i dont know what your trying to say but your projector is svga 800x600 no matter how you slice it.
stack all the 800x600 lcd's you want you are not getting a higher resolution than svga
you may get a better picture in the way of screen door but thats about it
Resolution in color LCD panels already includes the 3x for the colors.
Basically, an 800x600 panel is 2400x600 when you count the colors separately.
Some cheap small panel actually count the color pixels seperately.
If you ever see 960x240 pixels, you should be aware that this is really 320x240 being counted in a cheating sort of way.
Basically, an 800x600 panel is 2400x600 when you count the colors separately.
Some cheap small panel actually count the color pixels seperately.
If you ever see 960x240 pixels, you should be aware that this is really 320x240 being counted in a cheating sort of way.
Apo,
Sounds like your prism arrangement is actually an X-Cube, a very special type of collection of prisms.
These are used in commercial projectors to re-combine component color signals as you are explaining. They can also be used for separation.
They rely for their magic on special ultra thin coatings and are basically dichroic mirrors slapped onto prisms.
Take a look at this:
http://www.us.schott.com/english/applications/digitalprojection/opticalengine/xcubes.html
Is this what you are seeing in you commercial projector?
Sounds like your prism arrangement is actually an X-Cube, a very special type of collection of prisms.
These are used in commercial projectors to re-combine component color signals as you are explaining. They can also be used for separation.
They rely for their magic on special ultra thin coatings and are basically dichroic mirrors slapped onto prisms.
Take a look at this:
http://www.us.schott.com/english/applications/digitalprojection/opticalengine/xcubes.html
Is this what you are seeing in you commercial projector?
Okay, the 3x as much resolution idea here is complete bunk. Trust me, I have been doing graphics for YEARS. I know about resolution.
If you use 3 800x600 panels, one for each color component, and you are a good little DIYer and line up the pixels correctly, you will have an absolutely superb 800x600 full-color image. (Actually the "full color" part is a lie, because it only does whatever R, G, and B you end up with, and an approximation of the stuff in between; no infrared or ultraviolet, but most people haven't noticed yet, so no worries.)
The final image is still 800x600. The quality will be superb, especially with the idea of LED lamps instead of full-spectrum lamps, but the cost will probably be prohibitive, for a DIY project.
Actually, scratch that--buying bulk LEDs, I'll bet you could get something infinitely superior to the best Pro LCD projector out there, and still only pay about the same as an entry-level pro LCD projector.
Someone draw up plans and I'll start building.
If you use 3 800x600 panels, one for each color component, and you are a good little DIYer and line up the pixels correctly, you will have an absolutely superb 800x600 full-color image. (Actually the "full color" part is a lie, because it only does whatever R, G, and B you end up with, and an approximation of the stuff in between; no infrared or ultraviolet, but most people haven't noticed yet, so no worries.)
The final image is still 800x600. The quality will be superb, especially with the idea of LED lamps instead of full-spectrum lamps, but the cost will probably be prohibitive, for a DIY project.
Actually, scratch that--buying bulk LEDs, I'll bet you could get something infinitely superior to the best Pro LCD projector out there, and still only pay about the same as an entry-level pro LCD projector.
Someone draw up plans and I'll start building.
neededandwanted, that is exactly the prism in my projector. It would work for this idea i think. what is the cost of one of these cubes?
What i am stating about my projector is in the manual. I dont mean to go against anyone but that is what it says in the manual, written by engineers. I think there is a big difference in having one panel to display all the colors oposed to 3 seperate panels displaying colors.
ap0
What i am stating about my projector is in the manual. I dont mean to go against anyone but that is what it says in the manual, written by engineers. I think there is a big difference in having one panel to display all the colors oposed to 3 seperate panels displaying colors.
ap0
ap0the0sis said:
Some manufacturers mark their products as 800xRGBx600. expecially on those smal LCDs. since three R. G. and B. dots are really one on LCD screen, this is just a market tool. for example if you search for 6" lcd monitor, you will see spec like: 960 (H) x 234 (V). It should be translated to 320x 234.
18Wheeler
ok so if u get a 2.2" lcd with a native reso of 320x234 and a 6"lcd with a native of 320x234 the pixels on the 2.2" should be smaller right? therfore giving u a higher reso for the size of the lcd? but the end effect should be the same also after projected say at a screen of 100"?
Thanx Trev
ok so if u get a 2.2" lcd with a native reso of 320x234 and a 6"lcd with a native of 320x234 the pixels on the 2.2" should be smaller right? therfore giving u a higher reso for the size of the lcd? but the end effect should be the same also after projected say at a screen of 100"?
Thanx Trev
Resolution and size are independant of each other. If I take a 14" monitor and a 24" monitor and feed a 640x480 signal into each, they are both still running at 640x480. The pixels on the 24" monitor will be a lot bigger.
We're getting into this idea of "convergence" now, and that tends to muddy the waters quite a bit.
If you assume that a pixel consists of a red, green, and a blue component, then 640x480 really is 640x480. Marketing people will say 1920x480, because there are 3 "pixels" in each of the pixels on the display, but one is painted red, one blue, and one green, and in a perfect world, they would all merge together into one pixel anyway, so this argument is moot. "Look! Due to a flaw in the nature of LCD displays, our display has three apparent pixels where there should only be one!! It looks horrible! Buy it!!!"
I've never liked LCDs much.... Trinitron CRTs have just about perfect convergence if it's adjusted properly, but LCDs can't ever have perfect convergence, unless they're black and white.
This is why your idea is so appealing--you take three black an white images, each controlling one color component, and then merge them together--the convergence is perfect, the resolution is exact, the screen door effect disappears, you get better color out of it, and focusing the darn thing doesn't have nearly as many tradeoffs to worry about.
The downside? Cost and complexity. Weigh that against the advantages (no screen door, perfect convergence, better color vibrance, etc) and you get another tradeoff (surprise, surprise) between cost and complexity, versus visual quality.
When I make my projector, this is the style I will be using, no doubt about it. I just can't stand when convergence is wrong...
We're getting into this idea of "convergence" now, and that tends to muddy the waters quite a bit.
If you assume that a pixel consists of a red, green, and a blue component, then 640x480 really is 640x480. Marketing people will say 1920x480, because there are 3 "pixels" in each of the pixels on the display, but one is painted red, one blue, and one green, and in a perfect world, they would all merge together into one pixel anyway, so this argument is moot. "Look! Due to a flaw in the nature of LCD displays, our display has three apparent pixels where there should only be one!! It looks horrible! Buy it!!!"
I've never liked LCDs much.... Trinitron CRTs have just about perfect convergence if it's adjusted properly, but LCDs can't ever have perfect convergence, unless they're black and white.
This is why your idea is so appealing--you take three black an white images, each controlling one color component, and then merge them together--the convergence is perfect, the resolution is exact, the screen door effect disappears, you get better color out of it, and focusing the darn thing doesn't have nearly as many tradeoffs to worry about.
The downside? Cost and complexity. Weigh that against the advantages (no screen door, perfect convergence, better color vibrance, etc) and you get another tradeoff (surprise, surprise) between cost and complexity, versus visual quality.
When I make my projector, this is the style I will be using, no doubt about it. I just can't stand when convergence is wrong...
ap0the0sis said:
No idea about the cost on one of these. The manufacturer will likely sell them in lots of 10,000 to start. They will usually make an eval kit available, that will either be cheap, or free, or expensive. By this, I mean that they price the eval kits out of the range of the DIY crowd (a DLP eval kit with a single panel runs $10,000 USD from TI) but will give them to big companies. Basically, they send samples and kits to the big companies and labs that they know of already. Typically, they also send along an invoice for the big bucks, but never expect it to be paid. They also send out samples where the lab promises to retun them after 6 months (again not expecting to get them back.)
As with all DIY parts, the game is to go hunting.
I wish I had a better answer for you.
There will be no difference in resolution. You can certainly minimize the screen door effect by the way you overlay the 3 layers (3 colors) on the screen. You can overlap them to light up all of the spaces in between the pixels. This is similar to the way that paper printing overlaps their "screens" to avoid moire patterns.
Do you get more resolution? No. Does it look better? Yes. Would they do this with single panels if they could? Yes. Are you gonna have alignment problems? Yes. Is the alignment going to be different when the PJ gets warm? Possibly.
Make sure that all of the 3 color images are in alignment before any keystone correction is done anywhere. You will probably want to mount your panels with some fine adjustment screws that can be accessed with the projector is running and hot.
If you want to quote what is in your manual. We can get to the bottom of what everyone is apparently disagreeing on.
wow, what a reply.
its been stated that filtering the light to be red, green and blue is no good because we loose 2/3 light on through the filter. so how can the lcds be configured so that they display red, green and blue, independantly?
i dont think it would cost more to build than what most of you have already spent experimenting. 3 lcd panels $60.00 each on ebay or $110.00 each from PE. lens and compnents can come from ebay and other cheap sources. automotive lamps (with reflectors, fog lamps?) could probably be used, or halogen lamps to keep costs low or even MH if you have them.
prism... hmm not sure about that. could plexi glass be used to make this prism? does it have to be glass? anyone know of a glass shop that accepts requests?😕
the whole thing would probably fit inside a cool computer case. ehh? p/s included.
ap0
its been stated that filtering the light to be red, green and blue is no good because we loose 2/3 light on through the filter. so how can the lcds be configured so that they display red, green and blue, independantly?
i dont think it would cost more to build than what most of you have already spent experimenting. 3 lcd panels $60.00 each on ebay or $110.00 each from PE. lens and compnents can come from ebay and other cheap sources. automotive lamps (with reflectors, fog lamps?) could probably be used, or halogen lamps to keep costs low or even MH if you have them.
prism... hmm not sure about that. could plexi glass be used to make this prism? does it have to be glass? anyone know of a glass shop that accepts requests?😕
the whole thing would probably fit inside a cool computer case. ehh? p/s included.
ap0
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