Rox, you misunderstood what I was trying to say... you'd need to split light (or have three light sources) and use a prism to put them back together, just like commercial projectors do... although making three DIY projectors would work too, but then you'd be in big $$ after buying lenses/etc. Actually it wouldn't be too bad I think... it'd be like having a CRT projector (three seperate projections that merge on the screen).
Stacking three color LCD's one after another would definitely never work.
Stacking three color LCD's one after another would definitely never work.
yes, i know what you mean but there is a wrong desing in your setup.
your lcd is in color. if you feed red to a color lcd you have 2 posibilities; only feed red, so the image is red (blue and green pixels will always be black so the brigtness will be 3 times less) or you can feed red signal to the thee comonents so the image will be black and white but the information shown on the lcd will be red component (do you understand this?). In the second case, the tree pixels will work so the image will be 3 times brighter but the need of a color layer (red in this case) is necesar so the image will decrease 1/3 times. So we have always the light will be 3 times less than normal usage of the lcd.
I repeat that the main advantage of the 3 lcd setup is the brightness (because they first split the light by color components, so from a bulb they direct red light to red lcd, blue light to blue lcd and green light to green lcd) so ther eis no waste of light, and then they combine again the 3 images.
you cant do it with a color lcd. the lcd must be mococromatic.
your lcd is in color. if you feed red to a color lcd you have 2 posibilities; only feed red, so the image is red (blue and green pixels will always be black so the brigtness will be 3 times less) or you can feed red signal to the thee comonents so the image will be black and white but the information shown on the lcd will be red component (do you understand this?). In the second case, the tree pixels will work so the image will be 3 times brighter but the need of a color layer (red in this case) is necesar so the image will decrease 1/3 times. So we have always the light will be 3 times less than normal usage of the lcd.
I repeat that the main advantage of the 3 lcd setup is the brightness (because they first split the light by color components, so from a bulb they direct red light to red lcd, blue light to blue lcd and green light to green lcd) so ther eis no waste of light, and then they combine again the 3 images.
you cant do it with a color lcd. the lcd must be mococromatic.
How about this... you supposedly would get almost 3x the light from a single light source... only problem I see are splitting video to R/G/B w/ sync on all three, and convergence being a major pain in the butt. You would use a longer FL "back" fresnel on the two side colors and shorter one for center color. The setup would only cost you 2x extra LCD panels and 2x extra lenses (granted, most expensive parts of the system). I still think maybe doable with good results on a smaller/cheaper LCD system. Lenses are also MUCH cheaper if you don't need a wide FOV, like for use with small LCD's.
An externally hosted image should be here but it was not working when we last tested it.
well, first of all, you have not added the three images, you must mix them by semi-mirror kind of spltiters.
using diferent focal field fresnells will not work, since there is 1 panel to a fixed distance from the triplet and there are other 2 panels to another distance from the panel, could you tell me where will the image be projected? (you know that each lcd triplet distance has it´s own throw?)
but the main problem is that you have not monocromatic lcds.
the 3 lcd setups only work with RGB splited light sources. do you understand this?
using diferent focal field fresnells will not work, since there is 1 panel to a fixed distance from the triplet and there are other 2 panels to another distance from the panel, could you tell me where will the image be projected? (you know that each lcd triplet distance has it´s own throw?)
but the main problem is that you have not monocromatic lcds.
the 3 lcd setups only work with RGB splited light sources. do you understand this?
Rox said:
Yep, that's what I mean by convergence. Think of a CRT Projector... three images projected, each a single primary color only, and they're shifted together optically to make a completed picture.
Rox said:
If you adjust the back fresnel ONLY, for example the one in the middle gets a 220mm focal, and the two outside get a 330mm or 550mm focal, you leave the front fresnel the same on all three. This way you can have seperate back focal lengths, but identical front focal lengths going into the lenses.
Rox said:
Again, compare this to a CRT projector, rather than a commercial LCD projector... slightly different method, but similar results. Like I said tho, convergence would be a PITA heheh.
sorry i undestood the bottom circle was the projection lens (it is the lamp) sorry about it. (messed it all 
)
Yes, three projection lenses with shifting will work perfectly mixing the 3 images. That´s fine
now let me ask, your lcds are color? (RGB pixels on each?)
you are shining white light to all lcds, are you?
(remenber that on comertial 3 lcd setups they shine red light to the red lcd and blue light to the blue lcd and green light to the green lcd.)
)Yes, three projection lenses with shifting will work perfectly mixing the 3 images. That´s fine
now let me ask, your lcds are color? (RGB pixels on each?)
you are shining white light to all lcds, are you?
(remenber that on comertial 3 lcd setups they shine red light to the red lcd and blue light to the blue lcd and green light to the green lcd.)
Yeah, the solution I drew up was white light, through color LCD's each only allowing a single primary color to pass, and converged after projection.
Unfortunately, a commercial LCD setup requires several things we don't have...
1) high res greyscale LCD's
2) splitting / combining prisms
So I'm thinking it's not feasable at all to try and mimic a commercial setup... maybe the prism's could be doable, but I don't think the greyscale LCD's can be sourced at all.
My plan was kind of a "work around" of sorts.
Unfortunately, a commercial LCD setup requires several things we don't have...
1) high res greyscale LCD's
2) splitting / combining prisms
So I'm thinking it's not feasable at all to try and mimic a commercial setup... maybe the prism's could be doable, but I don't think the greyscale LCD's can be sourced at all.
My plan was kind of a "work around" of sorts.
then you will loss more light than using only 1 lcd to full color.
first you have 1/3 light from the bulb to each lcd, then again 1/3 because you only have 1 color (other two will block the light) finally you have 1/9 of the light from the bulb.
If you take all the light from the bulb and then make 1 lcd work full color (RGB) then you have much more light than the previows setup.
If you have 3 monocromatic lcd and the spliters/color filters/..... then yes, you can go for 3 lcd setup, but it is not as easy as thought
first you have 1/3 light from the bulb to each lcd, then again 1/3 because you only have 1 color (other two will block the light) finally you have 1/9 of the light from the bulb.
If you take all the light from the bulb and then make 1 lcd work full color (RGB) then you have much more light than the previows setup.
If you have 3 monocromatic lcd and the spliters/color filters/..... then yes, you can go for 3 lcd setup, but it is not as easy as thought
Actually, you should be able to get almost same amount of light out of the three lens/LCD setup... look at the picture above... to get the light to seperate LCD's, I'm taking SEPERATE light arcs to each one... normally, you'd only get a single one of those arcs to a single LCD setup, and the rest is thrown away... as you said, each light arc is reduced by 1/3 or so because of the LCD (but we have three seperate light paths now). Then, after the LCD, you're then projecting the three seperate arcs out... so once the light gets back to the screen, even with the 1/3 loss through the LCD, you therotically get the same amount of light onto the screen as you would with a single LCD setup, because there's three seperate projections of light that combine.
There are two places where you WILL lose light with the three-setup though:
1) The arcs to the side LCD's are narrower than the middle arc, and you'd have to reduce the brightness on the middle LCD to compensate...
2) you can't use a reflector behind the bulb... although if you had the right shape mirror surface, you can still put something behind the bulb and project the back-cast light onto the three light arcs if you did the calculations right.
You'd still certainly get most of the light, definitely way more than 1/9th.
There are two places where you WILL lose light with the three-setup though:
1) The arcs to the side LCD's are narrower than the middle arc, and you'd have to reduce the brightness on the middle LCD to compensate...
2) you can't use a reflector behind the bulb... although if you had the right shape mirror surface, you can still put something behind the bulb and project the back-cast light onto the three light arcs if you did the calculations right.
You'd still certainly get most of the light, definitely way more than 1/9th.
sorry no picture on your last post .
there i did a mistake on the calcs;
(i always will compare 3LCD setup VS 1LCD setup)
we have 3 times less light on each lcd, then we have 1/3 area of each lcd that works (mean blue and green will always block light on the red feed lcd) that means 1/3 light efficiency again, and finally (i forgot lats time) we have 1/3 light eficiency on the lcd because you are shining white light from the bulb to a color layered lcd. then you add tree lcds by the shifting lens so 3X.
we have 1/3*1/3*1/3*3=1/9 on the 3 lcd setup.
if we have 1 lcd setup;
full light from the bulb goes to the lcd, so 1
full area on the lcd will work , so 1
white light shining on colored lcd so 1/3 efficiency.
total 1 lcd setup eficiency: 1/3
total 3lcd setup efficiency; 1/9
.there i did a mistake on the calcs;
(i always will compare 3LCD setup VS 1LCD setup)
we have 3 times less light on each lcd, then we have 1/3 area of each lcd that works (mean blue and green will always block light on the red feed lcd) that means 1/3 light efficiency again, and finally (i forgot lats time) we have 1/3 light eficiency on the lcd because you are shining white light from the bulb to a color layered lcd. then you add tree lcds by the shifting lens so 3X.
we have 1/3*1/3*1/3*3=1/9 on the 3 lcd setup.
if we have 1 lcd setup;
full light from the bulb goes to the lcd, so 1
full area on the lcd will work , so 1
white light shining on colored lcd so 1/3 efficiency.
total 1 lcd setup eficiency: 1/3
total 3lcd setup efficiency; 1/9
Rox said:sorry no picture on your last post
we have 3 times less light on each lcd
Check the pic below, I'm taking three seperate light arcs from the light source. With a 1 LCD setup, you're throwing away the two other arcs (wasted light). So I get 3x light from the source.
Here's the pic again:
An externally hosted image should be here but it was not working when we last tested it.
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